4-Amino-6-phenyl-5,6-dihydroimidazo[1,5-a]pyrazin-3(2H)-one derivatives as inhibitors of beta-secretase (BACE)

ABSTRACT

The present invention relates to novel 5,6-dihydroimidazo[1,5-a]pyrazin-3(2H)-one derivatives as inhibitors of beta-secretase, also known as beta-site amyloid cleaving enzyme, BACE, in particular BACE1 and/or BACE2 (wherein BACE1, is also known as Asp2, or memapsin2 and BACE2 is also known as Asp1, Memapsin 1 or DRAP). The invention is also directed to pharmaceutical compositions comprising such compounds, to processes for preparing such compounds and compositions, and to the use of such compounds and compositions for the prevention and treatment of disorders in which beta-secretase is involved, such as Alzheimer&#39;s disease (AD), mild cognitive impairment, senility, dementia, dementia with Lewy bodies, Down&#39;s syndrome, dementia associated with stroke, dementia associated with Parkinson&#39;s disease, dementia of the Alzheimer&#39;s type, dementia associated with beta-amyloid, age-related macular degeneration, type 2 diabetes and other metabolic disorders.

CROSS REFERENCE TO RELATED APPLICARIONS

This application is the national stage of PCT Application No.PCT/EP2014/062283, filed Jun. 12, 2014, which claims priority fromEuropean Patent Application No. 13171723.3,filed Jun. 12, 2013, theentire disclosures of which are hereby incorporated in their entirety.

FIELD OF THE INVENTION

The present invention relates to novel5,6-dihydroimidazo[1,5-a]pyrazin-3(2H)-one derivatives as inhibitors ofbeta-secretase, also known as beta-site amyloid cleaving enzyme, BACE,in particular BACE1 and/or BACE2 (wherein BACE1, is also known as Asp2,or memapsin2 and BACE2 is also known as Asp1, Memapsin 1 or DRAP). Theinvention is also directed to pharmaceutical compositions comprisingsuch compounds, to processes for preparing such compounds andcompositions, and to the use of such compounds and compositions for theprevention and treatment of disorders in which beta-secretase isinvolved, such as Alzheimer's disease (AD), mild cognitive impairment,senility, dementia, dementia with Lewy bodies, Down's syndrome, dementiaassociated with stroke, dementia associated with Parkinson's disease,dementia of the Alzheimer's type, dementia associated with beta-amyloid.In addition to Alzheimer's disease, Down syndrome, and related diseases,BACE inhibition may find therapeutic and/or prophylactic treatment usein conditions such as traumatic brain injury (TBI), temporal lobeepilepsy (TLE), hypoxia, ischemia, cellular stress, neuroinflammatorydisorders, disruptions in cerebral metabolism, age-related maculardegeneration, Sjogren syndrome, Spinocerebellar ataxia 1,Spinocerebellar ataxia 7, Whippel's disease and Wilson's disease,age-related macular degeneration, amyotrophic lateral sclerosis (ALS),arterial thrombosis, autoimmune/inflammatory diseases, cardiovasculardiseases such as myocardial infarction and stroke, dermatomyositis,gastrointestinal diseases, Glioblastoma multiforme, Graves' Disease,Huntington's Disease, inclusion body myositis (IBM), inflammatoryreactions, Kaposi Sarcoma, Kostmann Disease, lupus erythematosus,macrophagic myofasciitis, juvenile idiopathic arthritis, granulomatousarthritis, type 2 diabetes and other metabolic disorders, malignantmelanoma, multiple myeloma, and rheumatoid arthritis, hypertension,malignant melanoma and multiple melanoma and breast cancer.

BACKGROUND OF THE INVENTION

Alzheimer's disease (AD) is a neurodegenerative disease and the mostcommon cause of dementia. Early memory problems and gradual andprogressive decline in cognitive functions beyond normal ageing arecharacteristic for AD. Post-mortem studies have shown theneuropathological hallmarks of the disease include extracellular amyloidplaques mainly consisting of 38 to 43 amino acids long peptides calledAβ peptide and intracellular neurofibrillary tangles withhyperphosphorylated TAU protein as the characteristic component.

Aβ peptides are generated in the amyloidogenic pathway from the AmyloidPrecursor Protein (APP). In this pathway, Aβ peptides are generated bythe sequential action of two proteases, β- and γ-secretase. Theβ-secretase activity is exerted by the β-site APP cleaving enzyme 1(BACE1) and BACE1 mediated APP cleavage results in shedding of theextracellular APP ectodomain (sAPPβ). The remaining membrane-boundC-terminal fragment (C99) is further processed by γ-secretase, whichcatalyzes an unusual proteolysis within the transmembrane region,resulting in the release of the APP intracellular domain (AICD) in thecytosol and the exocytosis of Aβ peptides in the extracellularenvironment. The majority of Aβ produced is 40-amino acid residues inlength (Aβ40). Although the 42-residue form (Aβ42) is a minor species,it more readily aggregates to produce fibrils and ultimately amyloidplaques.

Next to the pathology also human genetics studies strongly suggest thatAβ plays a central role in AD pathogenesis. Today, over 200 autosomaldominant mutations that cause familial AD (FAD) have been found in thegenes for APP and presenilin, the active subunit of γ-secretase. Thesemutations invariably lead to either increased Aβ42 to Aβ40 ratio orover-production of total Aβ. Notably, the FAD mutations in APP are foundnear the β- and γ-secretase cleavage sites and make APP a more efficientsubstrate for endoproteolysis by the secretases. Of particular relevancehere are the K670N; M671L (Swedish) double mutation and the A673Vmutation that are adjacent to the β-secretase cleavage site and causeFAD by increasing β-secretase processing and total Aβ production.Interestingly genetic variants have been identified that protect againstAD. A low-frequency mutation in APP, the A673T coding substitution, wasrecently shown to be associated with decreased risk of AD and reducedcognitive decline in the elderly (Jonsson et al. 2012, Nature 488,96-99). APP harboring the A673T substitution—located two amino acidsC-terminal to the β-secretase cleavage site is less efficiently cleavedby β-secretase, leading to a ˜40% reduction in Aβ production in vitro.

Cleavage of APP by Beta-site APP Cleaving Enzyme1 (BACE1) is the ratelimiting step in the generation of the Aβ peptide. BACE1 is amembrane-bound asparty1 protease that is optimally active at a slightlyacidic pH. Although BACE1 is localized in various organelles, itsactivity is reported to be at a maximum in endosomes and to a lowerextend in the trans golgi network (TGN), hence most APP is cleaved byBACE1 in the endocytic compartment. Evidence that BACE-1 is the soleβ-secretase activity in the brain was provided by the observations thatBACE-1 knockout mice completely lacked both β-secretase enzyme activityand the product of β-cleavage, CTF99 (Roberds et al., 2001, Hum.

Mol. Genet. 10, 1317-1324, Luo et al., 2001, Nat. Neurosci. 4, 231-232).Ongoing clinical trials with BACE1 inhibitors confirm that BACE1 is thesole β-secretase activity in human brain, since pharmacological BACE1inhibition blocks Aβ production.

Soon after the discovery of BACE1, a related membrane-bound asparticprotease BACE2 was identified that shares 64% amino acid similarity toBACE1. Although BACE2 can generate Aβ in vitro, it appears not to do soin vivo as mentioned above. BACE1 and its homologue BACE2 are members ofthe pepsin-like family of aspartic proteases (cathepsin D and E, pepsinA and C, renin, napsin A). They display a typical bilobal structure withthe catalytic site located at the interface between the N- and theC-terminal lobe (Hong et al, 2000, Science 290, 150-153, Ostermann etal, 2006, Journal of molecular biology, 355, (2), 249-61). BACE1 and 2are anchored to the cell membrane via a transmembrane domain, which,together with several unique amino acid stretches and the arrangement ofthe three disulfide bridges (Haniu et al., 2000, J. Biol. Chem. 275,21099-21106) sets BACE apart from the rest of the pepsin family andfacilitates the generation of relatively specific inhibitors for BACE1and 2.

Next to APP a variety of CNS and peripheral BACE1 substrates andassociated functions have been described (Hemming et al. 2009, PLoS ONE4, e8477, Kuhn et al. 2012, EMBO J. 31, 3157-3168; Zhou et al. 2012, J.Biol. Chem. 287, 25927-25940, Stutzer et al. 2013, J. Biol. Chem. 288,10536-10547, reviewed in Vassar et al., J. Neurochem. (2014)10.1111/jnc.12715). Examples of BACE1 substrates are L1, CHL1, GLG1,PAM, SEZ6, SEZ6L, Jag1, NRG1, NaVβ2, VEGFR1 and APLP1. ConsequentlyBACE1 has a wide variety of potential physiologic functions including,but not exclusively in cell differentiation, immunoregulation,myelination, synaptic development and plasticity, cell death,neurogenesis and axonal guidance (Wang et al. Trends in PharmacologicalSciences, April 2013, Vol 34, No. 4, pp. 215-225; Yan and Vassar LancetNeurol. 2014, Vol. 13, pp. 319-329; Yan et al. J Alzheimers Dis. 2014,Vol. 38, No. 4, pp. 705-718).

For example in BACE1 knock-out mice, loss of cleavage of neuregulin 1(NRG1) type III resulted in impaired post-natal myelination in the PNAand CNS (Fleck et al. 2012, Curr. Alzheimer Res. 9, 178-183; Willem etal. 2009, Semin. Cell Dev. Biol. 20, 175-182). Loss of cleavage of NRG1type I results in abnormal muscle spindle formation and maintenance andassociated defects in coordinated movement (Cheret et al. 2013). BACE1processing of β-subunits of voltage-gated sodium channels controlscell-surface NaV channel density, neuronal excitability, and seizuresusceptibility (Kim et al. 2011, J. Biol. Chem. 286, 8106-8116).BACE1-dependent CHL1 cleavage is known to be involved in axon outgrowthand neuronal survival (Naus et al. 2004, J. Biol. Chem. 279,16083-16090). BACE1-dependent Jag1 cleavage regulates post-natalneurogenesis and astrogenesis by modulating Notch 1 signalling.

Therefore, in addition to Alzheimer's disease, Down syndrome, andrelated diseases, BACE inhibition may find therapeutic and/orprophylactic treatment use in conditions such as traumatic brain injury(TBI), temporal lobe epilepsy (TLE), hypoxia, ischemia, cellular stress,neuroinflammatory disorders, disruptions in cerebral metabolism,age-related macular degeneration, Sjogren syndrome, Spinocerebellarataxia 1, Spinocerebellar ataxia 7, Whippel's disease and Wilson'sdisease, age-related macular degeneration, amyotrophic lateral sclerosis(ALS), arterial thrombosis, autoimmune/inflammatory diseases,cardiovascular diseases such as myocardial infarction and stroke,dermatomyositis, gastrointestinal diseases, Glioblastoma multiforme,Graves' Disease, Huntington's Disease, inclusion body myositis (IBM),inflammatory reactions, Kaposi Sarcoma, Kostmann Disease, lupuserythematosus, macrophagic myofasciitis, juvenile idiopathic arthritis,granulomatous arthritis, malignant melanoma, multiple myeloma, andrheumatoid arthritis.

Also BACE2 has a broad expression profile, with relative high expressionlevels in most different cell types and organs in the periphery andlower level of expression in astrocytes in the brain. As mentioned abovealso BACE2 has a broad spectrum of substrates as exemplified by thestudy in the pancreatic islets mentioned above (Stutzer et al. 2013).

BACE2 is expressed in pancreatic β cells, where it cleaves Tmem27(Esterházy et al. Cell Metabolism 2011). Inhibition of BACE2 thereforemay provide a potential mechanism to result in increased β cell mass,and a potential mode of action in the treatment or prevention of Type2diabetes

BACE2 is also known to be involved in the cleavage of APP (Wang et al.Trends in Pharmacological Sciences, April 2013, Vol. 34, No. 4, pp.215-225), IL-1R2 (Kuhn et al. J. Biol. Chem. 2007, Vol. 282, No. 16, pp.11982-11995), and pigment cell-specific melanocyte protein (PMEL)(Rochin et al. PNAS, Jun. 25, 2013, Vol. 110, No. 26, pp. 10658-10663),therefore indicating a potential application for BACE2 inhibitors in thetreatment of Down's syndrome, hypertension, malignant melanoma andmultiple melanoma. BACE2 is unregulated in human breast cancers (Kondohet al. Breast Cancer Res. Treat., 2003, Vol. 78, pp. 37-44), andtherefore BACE2 inhibitors may provide a potential in the treatment ofbreast cancers.

Inhibitors of BACE1 and/or BACE2 may thus be useful for the therapeuticand/or prophylactic treatment of Alzheimer's disease (AD), mildcognitive impairment, senility, dementia, dementia with Lewy bodies,Down's syndrome, dementia associated with stroke, dementia associatedwith Parkinson's disease, dementia of the Alzheimer's type, dementiaassociated with beta-amyloid. In addition to Alzheimer's disease, andrelated diseases, BACE inhibition may find therapeutic and/orprophylactic treatment use in conditions such as traumatic brain injury(TBI), temporal lobe epilepsy (TLE), hypoxia, ischemia, cellular stress,neuroinflammatory disorders, disruptions in cerebral metabolism,age-related macular degeneration, Sjogren syndrome, Spinocerebellarataxia 1, Spinocerebellar ataxia 7, Whippet's disease and Wilson'sdisease, age-related macular degeneration, amyotrophic lateral sclerosis(ALS), arterial thrombosis, autoimmune/inflammatory diseases,cardiovascular diseases such as myocardial, infarction and stroke,dermatomyositis, gastrointestinal diseases, Glioblastoma multiforme,Graves' Disease, Huntington's Disease, inclusion body myositis (IBM),inflammatory reactions, Kaposi Sarcoma, Kostmann Disease, lupuserythematosus, macrophagic myofasciitis, juvenile idiopathic arthritis,granulomatous arthritis, malignant melanoma, multiple myeloma, andrheumatoid arthritis, type 2 diabetes and other metabolic disorders,hypertension, malignant melanoma and multiple melanoma and breastcancer.

WO 2012/120023 (Janssen Pharmaceutica NV) discloses3,4-dihydro-pyrrolo[1,2-a]pyrazin-1-ylamine compounds useful as BACEinhibitors. WO 2012/057247 (Shionogi & Co., Ltd.) describes fusedaminodihydropyrimidine derivatives useful as BACE inhibitors.

SUMMARY OF THE INVENTION

It is the object of the present invention to provide compounds with BACEinhibitory activity. The present invention is directed to5,6-dihydroimidazo[1,5-a]pyrazin-3(2H)-one derivatives of Formula (I)

and the stereoisomeric forms thereof, wherein

-   R is selected from the group of C₁₋₄alkyl optionally substituted    with one or more substituents each independently selected from halo,    —CN, C₃₋₇cycloalkyl optionally substituted with one or more halo    substituents, and C₁₋₄alkyloxy optionally substituted with one or    more halo substituents; and C₃₋₇cycloalkyl optionally substituted    with one or more substituents each independently selected from halo,    —CN, and C₁₋₄alkyloxy optionally substituted with one or more halo    substituents;-   R¹ is selected from the group of hydrogen; halo; and C₁₋₄alkyl;-   R² is selected from the group of C₁₋₄alkyl optionally substituted    with one or more substituents each independently selected from    fluoro and C₁₋₄alkyloxy; and C₃₋₇cycloalkyl;-   R³ is in each instance an independently selected halo substituent;-   n is an integer selected from 1 and 2;-   R⁴ is selected from (a) and (b):

wherein R⁵ and R⁶ are each independently selected from the group of aryland heteroaryl, each of which may be optionally substituted with one ormore substituents each independently selected from the group of halo,—CN, C₁₋₄alkyl optionally substituted with one or more halosubstituents, and C₁₋₄alkyloxy optionally substituted with one or morehalo substituents;

-   wherein aryl is phenyl;-   wherein heteroaryl is a 5-membered aromatic heterocycle selected    from the group consisting of oxazole and pyrazole; or is a    6-membered aromatic heterocycle selected from the group consisting    of pyridinyl, pyrimidinyl and pyrazinyl;-   and the pharmaceutically acceptable salts and the solvates thereof.

Illustrative of the invention is a pharmaceutical composition comprisinga pharmaceutically acceptable carrier and any of the compounds describedabove. An illustration of the invention is a pharmaceutical compositionmade by mixing any of the compounds described above and apharmaceutically acceptable carrier. Illustrating the invention is aprocess for making a pharmaceutical composition comprising mixing any ofthe compounds described above and a pharmaceutically acceptable carrier.

Exemplifying the invention are methods of treating a disorder mediatedby the beta-secretase enzyme, comprising administering to a subject inneed thereof a therapeutically effective amount of any of the compoundsor pharmaceutical compositions described herein.

Further exemplifying the invention are methods of inhibiting thebeta-secretase enzyme, comprising administering to a subject in needthereof a therapeutically effective amount of any of the compounds orpharmaceutical compositions described herein.

An example of the invention is a method of treating or preventing adisorder selected from the group consisting of Alzheimer's Disease (AD),mild cognitive impairment (MCI), memory impairment, senility, dementia,dementia with Lewy bodies, dementia with progressive nuclear palsy,dementia with Cortico-basal degeneration, mixed dementia withAlzheimer's and vascular type, Alzheimer's disorder with difuse LewyBody disease, amyloid angiopathy, cerebral amyloid angiopathy,multi-infarct dementia, Down's syndrome, dementia associated withParkinson's disease, dementia of the Alzheimer's type, senile dementiaof the Alzheimer's type, vascular dementia, dementia due to HIV disease,dementia due to head trauma, dementia due to Huntington's disease,dementia due to Pick's disease, dementia due to Creutzfeldt-Jakobdisease, frontotemporal dementia, dementia pugilistica, dementiaassociated with beta-amyloid, amyloidosis of the brain and other organs(age and non-age related), Dutch type of hereditary cerebral haemorrhagewith amyloidosis, traumatic brain injury (TBI), temporal lobe epilepsy(TLE), hypoxia, ischemia, disruptions in cerebral metabolism,age-related macular degeneration, type 2 diabetes and other metabolicdisorders, amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS),arterial thrombosis, autoimmune/inflammatory diseases, cancer such asbreast cancer, cardiovascular diseases such as myocardial infarction andstroke, hypertension, dermatomyositis, prion disease (Creutzfeld-Jakobdisease), gastrointestinal diseases, Glioblastoma multiforme, Graves'Disease, Huntington's Disease, inclusion body myositis (IBM),inflammatory reactions, Kaposi Sarcoma, Kostmann Disease, lupuserythematosus, macrophagic myofasctitis, juvenile idiopathic arthritis,granulomatous arthritis, malignant melanoma, multiple myeloma,rheumatoid arthritis, Sjogren syndrome, SpinoCerebellar Ataxia 1,SpinoCerebellar Ataxia 7, Whippel's Disease and Wilson's Disease. Anadditional example of the invention is a method of treating a disorderselected from the group consisting of Alzheimer's disease, mildcognitive impairment, senility, dementia, dementia with Lewy bodies,cerebral amyloid angiopathy, multi-infarct dementia, Down's syndrome,dementia associated with stroke, dementia associated with Parkinson'sdisease, dementia of the Alzheimer's type and dementia associated withbeta-amyloid, preferably Alzheimer's disease, comprising administeringto a subject in need thereof, a therapeutically effective amount of anyof the compounds or pharmaceutical compositions described herein.

A further example of the invention is a method of treating aneurocognitive disorder (NCD) selected from a neurocognitive disorderdue to Alzheimer's disease, due to traumatic brain injury (TBI), due toLewy body disease, due to Parkinson's disease or to vascular NCD (suchas vascular NCD present with multiple infarctions), comprisingadministering to a subject in need thereof, a therapeutically effectiveamount of any of the compounds or pharmaceutical compositions describedherein.

Another example of the invention is any of the compounds described abovefor use in treating: (a) Alzheimer's Disease, (b) mild cognitiveimpairment, (c) senility, (d) dementia, (e) dementia with Lewy bodies,(f) Down's syndrome, (g) dementia associated with stroke, (h) dementiaassociated with Parkinson's disease, (i) dementia of the Alzheimer'stype, (j) dementia associated with beta-amyloid, (k) age-related maculardegeneration, (k) type 2 diabetes and (l) other metabolic disorders, ina subject in need thereof.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to compounds of Formula (I) as definedhereinbefore and pharmaceutically acceptable salts and solvates thereof.The compounds of Formula (I) are inhibitors of the beta-secretase enzyme(also known as beta-site cleaving enzyme, BACE, in particular BACE1(also known as Asp2 or memapsin 2), and/or BACE2 (also known as Asp1,Memapsin 1 or DRAP)), and may be useful in the treatment or preventionof Alzheimer's disease, mild cognitive impairment, senility, dementia,dementia associated with stroke, dementia with Lewy bodies, Down'ssyndrome, dementia associated with Parkinson's disease, dementia of theAlzheimer's type, dementia associated with beta-amyloid, age-relatedmacular degeneration, type 2 diabetes and other metabolic disorders,preferably Alzheimer's disease, mild cognitive impairment or dementia,type 2 diabetes and other metabolic disorders, more preferablyAlzheimer's disease and/or type 2 diabetes. Furthermore, the compoundsof Formula (I) may be useful in the treatment of neurocognitive disorderdue to Alzheimer's disease, due to traumatic brain injury (TBI), due toLewy body disease, due to Parkinson's disease or to vascular NCD (suchas vascular NCD present with multiple infarctions). In particular, thecompounds of Formula (I) may be useful in the treatment of Alzheimer'sdisease, mild cognitive impairment, senility, dementia, dementiaassociated with stroke, dementia with Lewy bodies, Down's syndrome,dementia associated with Parkinson's disease, dementia of theAlzheimer's type and dementia associated with beta-amyloid, preferablyAlzheimer's disease, mild cognitive impairment or dementia, morepreferably Alzheimer's disease. Furthermore, the compounds of Formula(I) may be useful in the treatment of neurocognitive disorder due toAlzheimer's disease, due to traumatic brain injury (TBI), due to Lewybody disease, due to Parkinson's disease or to vascular NCD (such asvascular NCD present with multiple infarctions). In particular, thecompounds of Formula (I) may be useful in the treatment or prevention ofAlzheimer's disease (or dementia of the Alzheimer's type, orneurocognitive disorder due to Alzheimer's disease). In particular, thecompounds of Formula (I) may be useful in the treatment or prevention oftype 2 diabetes.

In an embodiment, the present invention relates to compounds of Formula(I) as defined hereinabove, and stereoisomeric forms thereof, wherein

-   R is selected from the group of C₁₋₄alkyl optionally substituted    with one or more substituents each independently selected from halo,    —CN, C₃₋₇cycloalkyl optionally substituted with one or more fluoro    substituents, and C₁₋₄alkyloxy optionally substituted with one or    more fluoro substituents; and C₃₋₇cycloalkyl optionally substituted    with one or more substituents each independently selected from halo,    —CN, and C₁₋₄alkyloxy optionally substituted with one or more fluoro    substituents;-   R¹ is selected from the group of hydrogen; halo; and C₁₋₄alkyl;-   R² is C₁₋₄alkyl optionally substituted with one or more substituents    each independently selected from fluoro and C₁₋₄alkyloxy;-   R³ is in each instance an independently selected halo substituent;-   n is an integer selected from 1 and 2;-   R⁴ is

wherein R⁵ is selected from the group of aryl and heteroaryl, each ofwhich may be optionally substituted with one or more substituents eachindependently selected from the group of halo, —CN, C₁₋₄alkyl optionallysubstituted with one or more halo substituents, and C₁₋₄alkyloxyoptionally substituted with one or more halo substituents;

-   wherein aryl is phenyl;-   wherein heteroaryl is a 5-membered aromatic heterocycle selected    from the group consisting of oxazole and pyrazole; or is a    6-membered aromatic heterocycle selected from the group consisting    of pyridinyl, pyrimidinyl and pyrazinyl;-   and the pharmaceutically acceptable salts and the solvates thereof.

In an embodiment of the invention, R is C₁₋₄alkyl optionally substitutedwith 1-3 halo substituents, in particular fluoro, and the rest ofvariables are as defined in Formula (I) herein.

In an embodiment of the invention, R is C₁₋₄alkyl, in particular R ismethyl, and the rest of variables are as defined in Formula (I) herein.

In an embodiment of the invention, R¹ is hydrogen or halo, in particularhydrogen, and the rest of variables are as defined in Formula (I)herein.

In an embodiment of the invention, R² is C₁₋₄alkyl, in particularmethyl, and the rest of variables are as defined in Formula (I) herein.

In another embodiment of the invention, R⁴ is

wherein R⁵ is heteroaryl, optionally substituted with one or moresubstituents each independently selected from the group of halo, —CN,C₁₋₄alkyl optionally substituted with one or more halo substituents, andC₁₋₄alkyloxy;

-   wherein heteroaryl is a 5-membered aromatic heterocycle selected    from oxazole and pyrazole; or is a 6-membered aromatic heterocycle    selected from the group consisting of pyridinyl, pyrimidinyl and    pyrazinyl;-   and the rest of variables are as defined in Formula (I) herein.

In another embodiment of the invention, R⁴ is

wherein R⁵ is heteroaryl, optionally substituted with one or moresubstituents each independently selected from the group of halo, —CN,and C₁₋₄alkyl optionally substituted with one or more halo substituents;

-   wherein heteroaryl is a 5-membered aromatic heterocycle selected    from oxazole and pyrazole; or is a 6-membered aromatic heterocycle    selected from the group consisting of pyridinyl, pyrimidinyl and    pyrazinyl;-   and the rest of variables are as defined in Formula (I) herein.

In another embodiment, the present invention relates to compounds ofFormula (I) as defined hereinabove, and stereoisomeric forms thereof,wherein

-   R is methyl or CH₂CF₃;-   R¹ is hydrogen;-   R² is C₁₋₄alkyl, in particular methyl;-   R³ is halo, in particular fluoro; and n is 1;-   R⁴ is (a):

wherein R⁵ is oxazole, pyridinyl, pyrimidinyl or pyrazinyl, each ofwhich may be optionally substituted with one or two substituentsselected from the group of halo, —CN, C₁₋₄alkyl optionally substitutedwith one or more halo substituents, and C ₁₋₄alkyloxy;

-   and the pharmaceutically acceptable salts and the solvates thereof.

In another embodiment, the present invention relates to compounds ofFormula (I) as defined hereinabove, and stereoisomeric forms thereof,wherein

-   R is methyl;-   R¹ is hydrogen;-   R² is C₁₋₄alkyl;-   R³ is halo, in particular fluoro; and n is 1;-   R⁴ is (a):

wherein R⁵ is oxazole, pyridinyl, pyrimidinyl or pyrazinyl, each ofwhich may be optionally substituted with a substituent selected from thegroup of —CN, and C₁₋₄alkyl optionally substituted with one or more halosubstituents;

-   and the pharmaceutically acceptable salts and the solvates thereof.

In a further embodiment, the present invention relates to compounds ofFormula (I) as defined hereinabove, and stereoisomeric forms thereof,wherein

-   R is methyl;-   R¹ is hydrogen;-   R² is C₁₋₄alkyl;-   R³ is halo, in particular fluoro; and n is 1;-   R⁴ is (a):

wherein R⁵ is oxazole, pyridinyl, pyrimidinyl or pyrazinyl, each ofwhich may be optionally substituted with one or two substituents eachindependently selected from the group of halo, —CN, and C₁₋₄alkyloptionally substituted with one or more fluoro substituents;

-   and the pharmaceutically acceptable salts and the solvates thereof.

In another embodiment, the present invention relates to compounds ofFormula (I) as defined hereinabove, and stereoisomeric forms thereof,wherein

-   R is methyl;-   R¹ is hydrogen;-   R² is C₁₋₄alkyl;-   R³ is halo, in particular fluoro; and n is 1;-   R⁴ is (a):

wherein R⁵ is oxazole, pyridinyl and pyrimidinyl, each of which may beoptionally substituted with a substituent selected from the group ofhalo, —CN, and C₁₋₄alkyl;

-   and the pharmaceutically acceptable salts and the solvates thereof.

In a further embodiment,

-   R⁴ is (a):

wherein R⁵ is selected from one of (i)-(v) below:

-   (i) oxazole substituted with C₁₋₄alkyl; or-   (ii) pyridinyl, pyrimidinyl or pyrazinyl, each of which may be    optionally substituted with one or two substituents selected from    the group of halo, —CN, C₁₋₄alkyl, and C₁₋₄ alkyloxy; or-   (iii) pyridinyl substituted with a substituent selected from the    group of halo and —CN;-   (iv) pyridinyl substituted with one or two substituents selected    from the group of halo, —CN and methyl;-   (v) pyrazinyl substituted with C₁₋₄alkyloxy, in particular methoxy;-   and the pharmaceutically acceptable salts and the solvates thereof.

In a yet further embodiment, the present invention relates to compoundsof Formula (I) as defined hereinbefore wherein the quaternary carbonatom substituted with R² has a configuration as depicted in thestructure (I′) below wherein the5,6-dihydroimidazo[1,5-a]pyrazin-3(2H)-one core is in the plane of thedrawing, R² is projected below the plane of the drawing (with the bondshown with a wedge of parallel lines

) and Ar is projected above the plane of the drawing (with the bondshown with a bold wedge

)

wherein Ar is

in particular

Thus in a further embodiment, the compounds of Formula (I) as definedherein have in particular, Formula (I′a)

wherein R, R¹, R², and R⁴ are as defined herein.

Specific compounds according to the invention include:

-   (6R)-8-Amino-6-(2-fluoro-5-pyrimidin-5-ylphenyl)-2,6-dimethyl-5,6-dihydroimidazo[1,5-a]pyrazin-3(2H)-one;-   N-{3-[(6R)-8-Amino-2,6-dimethyl-3-oxo-2,3,5,6-tetrahydroimidazo[1,5-a]pyrazin-6-yl]-4-fluorophenyl}-2-methyl-1,3-oxazole-4-carboxamide;-   N-{3-[(6R)-8-Amino-2,6-dimethyl-3-oxo-2,3,5,6-tetrahydroimidazo[1,5-a]pyrazin-6-yl]-4-fluorophenyl}-5-cyanopyridine-2-carboxamide;-   N-{3-[(6R)-8-amino-2,6-dimethyl-3-oxo-5H-imidazo[1,5-a]pyrazin-6-yl]-4-fluoro-phenyl}-5-chloro-pyridine-2-carboxamide;-   N-{3-[(6R)-8-amino-2,6-dimethyl-3-oxo-2,3,5,6-tetrahydroimidazo[1,5-a]pyrazin-6-yl]-4-fluorophenyl}-5-fluoropyridine-2-carboxamide;-   N-{3-[(6R)-8-amino-2,6-dimethyl-3-oxo-2,3,5,6-tetrahydroimidazo[1,5-a]pyrazin-6-yl]-4-fluorophenyl}-5-methoxypyrazine-2-carboxamide;-   N-{3-[(6R)-8-amino-2,6-dimethyl-3-oxo-2,3,5,6-tetrahydroimidazo[1,5-a]pyrazin-6-yl]-4-fluorophenyl}-5-cyano-3-methylpyridine-2-carboxamide;-   N-{3-[(6R)-8-amino-6-methyl-3-oxo-2-(2,2,2-trifluoroethyl)-2,3,5,6-tetrahydroimidazo[1,5-a]pyrazin-6-yl]-4-fluorophenyl}-5-chloropyridine-2-carboxamide;-   N-{3-[(6R)-8-amino-6-methyl-3-oxo-2-(2,2,2-trifluoroethyl)-2,3,5,6-tetrahydroimidazo[1,5-a]pyrazin-6-yl]-4-fluorophenyl}-5-fluoropyridine-2-carboxamide;-   N-{3-[(6R)-8-amino-6-methyl-3-oxo-2-(2,2,2-trifluoroethyl)-2,3,5,6-tetrahydroimidazo[1,5-a]pyrazin-6-yl]-4-fluorophenyl}-5-methoxypyrazine-2-carboxamide;-   N-{3-[(6R)-8-amino-6-methyl-3-oxo-2-(2,2,2-trifluoroethyl)-2,3,5,6-tetrahydroimidazo[1,5-a]pyrazin-6-yl]-4-fluorophenyl}-5-cyanopyridine-2-carboxamide;-   and the pharmaceutically acceptable salts and solvates of such    compounds.

DEFINITIONS

“C₁₋₄alkyl” as used herein alone or as part of another group, defines asaturated, straight or branched, hydrocarbon radical having, 1, 2, 3 or4 carbon atoms, such as methyl, ethyl, 1-propyl, 1-methyl, butyl,1-methyl-propyl, 2-methyl-1-propyl, 1,1-dimethylethyl and the like.“C₁₋₄alkyloxy” shall denote an ether radical wherein C₁₋₄alkyl is asdefined herein. “Halo” shall denote fluoro, chloro and bromo.“C₃₋₇cycloalkyl” shall denote cyclopropyl, cyclobutyl, cyclopentyl,cyclohexyl and cycloheptyl.

Whenever the term “substituted” is used in the present invention, it ismeant, unless otherwise indicated or is clear from the context, toindicate that one or more hydrogens, preferably from 1 to 3 hydrogens,or from 1 to 2 hydrogens, or 1 hydrogen, on the atom or radicalindicated in the expression using “substituted” is replaced with aselection from the indicated group, provided that the normal valency isnot exceeded, and that the substitution results in a chemically stablecompound, i.e. a compound that is sufficiently robust to surviveisolation to a useful degree of purity from a reaction mixture, andformulation into a therapeutic agent.

The term “subject” as used herein, refers to an animal, preferably amammal, most preferably a human, who is or has been the object oftreatment, observation or experiment.

The term “therapeutically effective amount” as used herein, means thatamount of active compound or pharmaceutical agent that elicits thebiological or medicinal response in a tissue system, animal or humanthat is being sought by a researcher, veterinarian, medical doctor orother clinician, which includes alleviation of the symptoms of thedisease or disorder being treated.

As used herein, the term “composition” is intended to encompass aproduct comprising the specified ingredients in the specified amounts,as well as any product which results, directly or indirectly, fromcombinations of the specified ingredients in the specified amounts.

Hereinbefore and hereinafter, the term “compound of formula (I)” ismeant to include the addition salts, the solvates and the stereoisomersthereof.

The terms “stereoisomers” or “stereochemically isomeric forms”hereinbefore or hereinafter are used interchangeably.

The invention includes all stereoisomers of the compound of Formula (I)either as a pure stereoisomer or as a mixture of two or morestereoisomers.

Enantiomers are stereoisomers that are non-superimposable mirror imagesof each other. A 1:1 mixture of a pair of enantiomers is a racemate orracemic mixture.

Diastereomers (or diastereoisomers) are stereoisomers that are notenantiomers, i.e. they are not related as mirror images. Therefore, theinvention includes enantiomers, diastereomers, racemates.

The absolute configuration is specified according to theCahn-Ingold-Prelog system. The configuration at an asymmetric atom isspecified by either R or S. Resolved compounds whose absoluteconfiguration is not known can be designated by (+) or (−) depending onthe direction in which they rotate plane polarized light.

When a specific stereoisomer is identified, this means that saidstereoisomer is substantially free, i.e. associated with less than 50%,preferably less than 20%, more preferably less than 10%, even morepreferably less than 5%, in particular less than 2% and most preferablyless than 1%, of the other isomers. Thus, when a compound of formula (I)is for instance specified as (R), this means that the compound issubstantially free of the (S) isomer.

Furthermore, some of the crystalline forms for the compounds of thepresent invention may exist as polymorphs and as such are intended to beincluded in the present invention. In addition, some of the compounds ofthe present invention may form solvates with water (i.e., hydrates) orcommon organic solvents, and such solvates are also intended to beencompassed within the scope of this invention.

For use in medicine, the salts of the compounds of this invention referto non-toxic “pharmaceutically acceptable salts”. Other salts may,however, be useful in the preparation of compounds according to thisinvention or of their pharmaceutically acceptable salts. Suitablepharmaceutically acceptable salts of the compounds include acid additionsalts which may, for example, be formed by mixing a solution of thecompound with a solution of a pharmaceutically acceptable acid such ashydrochloric acid, sulfuric acid, fumaric acid, maleic acid, succinicacid, acetic acid, benzoic acid, citric acid, tartaric acid, carbonicacid or phosphoric acid. Furthermore, where the compounds of theinvention carry an acidic moiety, suitable pharmaceutically acceptablesalts thereof may include alkali metal salts, e.g., sodium or potassiumsalts; alkaline earth metal salts, e.g., calcium or magnesium salts; andsalts formed with suitable organic ligands, e.g., quaternary ammoniumsalts.

Representative acids which may be used in the preparation ofpharmaceutically acceptable salts include, but are not limited to, thefollowing: acetic acid, 2,2-dichloro-acetic acid, acylated amino acids,adipic acid, alginic acid, ascorbic acid, L-aspartic acid,benzenesulfonic acid, benzoic acid, 4-acetamidobenzoic acid,(+)-camphoric acid, camphorsulfonic acid, capric acid, caproic acid,caprylic acid, cinnamic acid, citric acid, cyclamic acid,ethane-1,2-disulfonic acid, ethanesulfonic acid,2-hydroxy-ethanesulfonic acid, formic acid, fumaric acid, galactaricacid, gentisic acid, glucoheptonic acid, D-gluconic acid, D-glucoronicacid, L-glutamic acid, beta-oxo-glutaric acid, glycolic acid, hippuricacid, hydrobromic acid, hydrochloric acid, (+)-L-lactic acid,(±)-DL-lactic acid, lactobionic acid, maleic acid, (−)-L-malic acid,malonic acid, (±)-DL-mandelic acid, methanesulfonic acid,naphthalene-2-sulfonic acid, naphthalene-1,5-disulfonic acid,1-hydroxy-2-naphthoic acid, nicotinic acid, nitric acid, oleic acid,orotic acid, oxalic acid, palmitic acid, pamoic acid, phosphoric acid,L-pyroglutamic acid, salicylic acid, 4-amino-salicylic acid, sebacicacid, stearic acid, succinic acid, sulfuric acid, tannic acid,(+)-L-tartaric acid, thiocyanic acid, p-toluenesulfonic acid,trifluoromethylsulfonic acid, and undecylenic acid. Representative baseswhich may be used in the preparation of pharmaceutically acceptablesalts include, but are not limited to, the following: ammonia,L-arginine, benethamine, benzathine, calcium hydroxide, choline,dimethylethanolamine, diethanolamine, diethylamine,2-(diethylamino)-ethanol, ethanolamine, ethylene-diamine,N-methyl-glucamine, hydrabamine, 1H-imidazole, L-lysine, magnesiumhydroxide, 4-(2-hydroxyethyl)-morpholine, piperazine, potassiumhydroxide, 1-(2-hydroxyethyl)-pyrrolidine, secondary amine, sodiumhydroxide, triethanolamine, tromethamine and zinc hydroxide.

The names of the compounds of the present invention were generatedaccording to the nomenclature rules agreed upon by the ChemicalAbstracts Service (CAS) using Advanced Chemical Development, Inc.,software (ACD/Name product version 10.01; Build 15494, 1 Dec. 2006 orACD/ChemSketch product version 12.5; Build 47877, 20 Apr. 2011) oraccording to the nomenclature rules agreed upon by the InternationalUnion of Pure and Applied Chemistry (IUPAC) using Advanced ChemicalDevelopment, Inc., software (ACD/Name product version 10.01.0.14105,October 2006). In case of tautomeric forms, the name of the depictedtautomeric form of the structure was generated. The other non-depictedtautomeric form is also included within the scope of the presentinvention.

PREPARATION OF THE COMPOUNDS A. Preparation of the Final CompoundsExperimental Procedure 1

Final compounds according to Formula (I) wherein R⁴ is —NHCOR⁵, herebynamed (I-a), can be prepared by reacting an intermediate compound ofFormula (II) with an intermediate of Formula (III) (Reaction Scheme 1).That reaction can be performed in a suitable solvent, such as methanol(MeOH), in the presence of a condensation agent, such as4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methyl-morpholinium chloride(DMTMM) under suitable reaction conditions, such as at a convenienttemperature, typically rt, for a period of time to ensure the completionof the reaction. An intermediate compound of Formula (III) can beobtained commercially or synthesized according to literature procedures.In Reaction Scheme 1, all variables are defined as in Formula (I).

Experimental Procedure 2

Alternatively final compounds according to Formula (I) wherein R⁴ is—R⁶, hereby named (I-b), can be prepared by reacting an intermediatecompound of Formula (IV) with an intermediate of Formula (V) (ReactionScheme 2). The reaction can be performed in a suitable solvent, such as,1,4-dioxane, in the presence of a suitable base, such as, sodiumcarbonate (Na₂CO₃), in the presence of a Pd-complex catalyst such as,1,1′-bis(diphenylphosphino)ferrocene-palladium(II) dichloridedichloromethane complex, under suitable reaction conditions, such as ata convenient temperature, typically 100° C., for a period of time toensure the completion of the reaction. An intermediate compound ofFormula (V) can be obtained commercially or synthesized according toliterature procedures. In Reaction Scheme 2, X is halo, R^(a) and R^(b)may be hydrogen or C₁₋₄alkyl, or may be taken together to form forexample a bivalent radical of formula —CH₂CH₂—, —CH₂CH₂CH₂—, or—C(CH₃)₂C(CH₃)₂— and all other variables are defined as in Formula (I).

B. Preparation of the Intermediate Compounds Experimental Procedure 3

Intermediate compound of Formula (II) can be prepared by acopper-catalyzed coupling reaction of an intermediate compound ofFormula (IV) with sodium azide in the presence of a copper catalyst,such as copper(I) iodide, in the presence of a suitable ligand, such as,N,N′-dimethylethylenediamine, in the presence of a suitable base, suchas Na₂CO₃ and in a suitable solvent, such as dimethylsulfoxide (DMSO).Degassing the reaction mixture with an inert gas, such as N₂ or argon,and heating the reaction mixture to high temperatures, such as about110° C., may enhance the reaction outcome. In Reaction Scheme 3, X ishalo and all other variables are defined as in Formula (I).

Experimental Procedure 4

Intermediate compound of Formula (IV) wherein X is halo, can be preparedby reacting an intermediate compound of Formula (VI) with an appropriatesource of ammonia such as, for example, ammonium chloride and/or ammoniain MeOH (Reaction Scheme 4). That reaction can be performed in asuitable solvent, such as, MeOH, under suitable reaction conditions,such as at a convenient temperature, typically 80° C., for a period oftime to ensure the completion of the reaction. In Reaction Scheme 4, Xis halo and all other variables are defined as in Formula (I).

Experimental Procedure 5

Intermediate compound of Formula (VI) wherein X is halo, can be preparedby reacting an intermediate compound of Formula (VII) in the presence ofsodium hydroxide and sodium hypochlorite (Reaction Scheme 5). Thatreaction can be performed in a suitable reaction-inert solvent, such as,tetrahydrofuran (THF), under suitable reaction conditions, such as at aconvenient temperature, typically rt, for a period of time to ensure thecompletion of the reaction. In Reaction Scheme 5, X is halo and allother variables are defined as in Formula (I).

Experimental Procedure 6

Intermediate compounds of Formula (VII) wherein R is a C₁₋₄alkyloptionally substituted with cyclopropyl or one or more halosubstituents, such as for example, a methyl group and X is halo, herebynamed (VII-a), can be prepared by reacting an intermediate compound ofFormula (VIII) with a suitable alkylating agent with an activatedleaving group, for example, methyl iodide in a reaction inert solvent,such as for example, acetone, in the presence of a suitable base suchas, for example, potassium carbonate, under suitable reactionconditions, such as at a convenient temperature, typically rt, for aperiod of time to ensure the completion of the reaction. In ReactionScheme 6, X is halo and all other variables are defined as in Formula(I).

Experimental Procedure 7

Intermediate compound of Formula (IV-a) can be prepared by reacting anintermediate compound of Formula (VII′) with an appropriate source ofammonia such as, for example, ammonium chloride and/or ammonia in MeOH(Reaction Scheme 7). That reaction can be performed in a suitablesolvent, such as, MeOH, under suitable reaction conditions, such as at aconvenient temperature, typically 80° C., for a period of time to ensurethe completion of the reaction.

Intermediate compound of Formula (VII′) can be prepared by reacting anintermediate compound of Formula (VII-b) in the presence of sodiumhypochlorite. That reaction can be performed in a suitablereaction-inert solvent, such as, tetrahydrofuran (THF), under suitablereaction conditions, such as at a convenient temperature, typically rt,for a period of time to ensure the completion of the reaction.

Intermediate compounds of Formula (VII-b) can be prepared by reacting anintermediate compound of Formula (VIII-a) with a suitablefluoroalkylating agent such as, for example, 2,2,2-trifluoroethylperfluorobutylsulfonate in a reaction inert solvent, such as forexample, acetonitrile, under suitable reaction conditions, such as at aconvenient temperature, typically 60° C., for 16 hours.

Intermediate compounds of Formula (VIII-a) can be prepared by reactingan intermediate compound of Formula (VIII) with a suitable alkylatingagent with an activated leaving group, for example, methyl iodide in areaction inert solvent, such as for example, ethanol, in the presence ofa suitable base such as, for example, sodium hydroxide, under suitablereaction conditions, such as at a convenient temperature, typically rt,for a period of time to ensure the completion of the reaction.

In Reaction Scheme 7, X is halo and all other variables are defined asin Formula (I).

Experimental Procedure 8

Intermediate compounds of Formula (VIII) wherein X is halo, can beprepared by reacting an intermediate compound of Formula (IX) with asuitable sulphur donating reagent for the synthesis of thioamides suchas, for example, phosphorous pentasulfide. That reaction can beperformed in a reaction inert solvent, such as for example, pyridine, inthe presence of a suitable base such as, for example, pyridine, undersuitable reaction conditions, such as at a convenient temperature,typically 110° C., for a period of time to ensure the completion of thereaction. In Reaction Scheme 8, X is halo and all other variables aredefined as in Formula (I).

Experimental Procedure 9

Intermediate compounds of Formula (IX) can be prepared from anintermediate compound of Formula (X) following art-known cyclizationprocedures. Said cyclization may conveniently be conducted by treatmentof an intermediate compound of Formula (X) with a suitable base, such assodium methoxide in MeOH, in a suitable reaction solvent, such as forexample MeOH under suitable reaction conditions, such as at a convenienttemperature, typically 60° C., for a period of time to ensure thecompletion of the reaction.

Alternatively, said cyclization may conveniently be conducted in twosteps. First by treatment of an intermediate compound of Formula (X)with a suitable base, such as lithium hydroxide, in a suitable reactionsolvent, such as for example a mixture of THF/water followed bytreatment with a condensation agent, such asO-(benzotriazol-1-yl)-N-N-N′-N′-tetramethyluronium hexafluorophosphate(HBTU), in the presence of a base, such as N,N-diisopropylethylamine, ina suitable solvent, such as N,N-dimethylformamide (DMF), under suitablereaction conditions, such as at a convenient temperature, typicallyranging between rt and 90° C., for a period of time to ensure thecompletion of the reaction.

Intermediate compounds of Formula (X) wherein R^(c) is C₁₋₄alkyl, can beprepared from an intermediate compound of Formula (XI) by removal of theprotecting group being carried out according to processes known in theart.

Intermediate compounds of Formula (XI) can be prepared from anintermediate compound of Formula (XII), wherein PG is a protecting groupof amines such as, for example, the tert-butoxycarbonyl group, followingart-known alkylation procedures. Said alkylation may conveniently beconducted by treatment of (XII) with an intermediate compound of Formula(XIII) with a suitable base such as, 1,8-diazabicyclo(5.4.0)undec-7-ene(DBU), in a suitable inert solvent such as, acetonitrile, under suitablereaction conditions, such as at a convenient temperature, typically 90°C., for a period of time to ensure the completion of the reaction.

An intermediate compound of Formula (XIII) can be obtained commerciallyor synthesized according to literature procedures. In Reaction Scheme 9,R^(c) is C₁₋₄alkyl, X is halo, PG is a protecting group and all othervariables are defined as in Formula (I).

Experimental Procedure 10

Intermediate compounds of Formula (IX) wherein R¹ is hydrogen and X ishalo, hereby named (IX-a), can be prepared by stirring an intermediatecompound of Formula (XIV) in a reaction inert solvent, such as forexample, DMSO, under suitable reaction conditions, such as at aconvenient temperature, typically ranging between 150° C. and 190° C.,for a period of time to ensure the completion of the reaction. InReaction Scheme 10, X is halo and all other variables are defined as inFormula (I).

Experimental Procedure 11

Intermediate compounds of Formula (XIV) can be prepared from anintermediate compound of Formula (X-a) following art-known cyclizationprocedures. Said cyclization may conveniently be conducted by treatmentof an intermediate compound of Formula (X-a) with a suitable base, suchas sodium methoxide in MeOH, in a suitable reaction solvent, such as forexample MeOH under suitable reaction conditions, such as at a convenienttemperature, typically 60° C., followed by treatment with a base such asan aqueous sodium hydroxide solution, under suitable reactionconditions, such as at a convenient temperature, typically rt, for aperiod of time to ensure the completion of the reaction.

Intermediate compounds of Formula (X-a) wherein R^(c) is C₁₋₄alkyl, canbe prepared from the corresponding intermediate compound of Formula(XI-a) by removal of the protecting group being carried out according toprocesses known in the art.

Intermediate compounds of Formula (XI-a) can be prepared from anintermediate compound of Formula (XII), wherein PG is a protecting groupof amines such as, for example, the tert-butoxycarbonyl group, followingart-known acylation procedures. Said alkylation may conveniently beconducted by treatment of (XII) with an intermediate compounds ofFormula (XIII-a) with a suitable base such as, for example, DBU, in asuitable inert solvent such as, acetonitrile, under suitable reactionconditions, such as at a convenient temperature, typically 90° C., for aperiod of time to ensure the completion of the reaction.

An intermediate compound of Formula (XIII-a) can be obtainedcommercially or synthesized according to literature procedures. InReaction Scheme 11, R^(c) is C₁₋₄alkyl, X is halo, PG is a protectinggroup and all other variables are defined as in Formula (I).

Experimental Procedure 12

Intermediate compounds of Formula (XII) can be prepared by reacting anintermediate compound of Formula (XVI) following art-known oxidationprocedures. Said oxidation may conveniently be conducted by treatment ofthe intermediate compound of Formula (XVI) with an oxidising agent suchas, for example, sodium metaperiodate in a suitable inert solvent suchas, for example, acetonitrile/water, in the presence of ruthenium(III)chloride, under suitable reaction conditions, such as at a convenienttemperature, typically rt, for a period of time to ensure the completionof the reaction.

Intermediate compounds of Formula (XVI) can be prepared by reacting theintermediate compounds of Formula (XV) following art-known sulfamidateformation procedures. Said transformation may conveniently be conductedby treatment of the intermediate compound of Formula (XV) with thionylchloride, in the presence of a base such as, for example, pyridine, in asuitable reaction-inert solvent, such as, for example, acetonitrile, atlow temperature such as, for example, −40° C., for example for 30 minand then at a moderately high temperature such as, for example, 25° C.,for example for 24 to 72 h.

Intermediate compounds of Formula (XV) wherein X is halo and PG is aprotecting group of amines such as, for example, the tert-butoxycarbonylgroup, can generally be prepared following art-known Strecker typeprocedures described in literature.

In Reaction Scheme 12, X is halo, PG is a protecting group and all othervariables are defined as in Formula (I).

Pharmacology

The compounds of the present invention and the pharmaceuticallyacceptable compositions thereof inhibit BACE (BACE1 and/or BACE2) andtherefore may be useful in the treatment or prevention of Alzheimer'sDisease (AD), mild cognitive impairment (MCI), memory impairment,senility, dementia, dementia with Lewy bodies, dementia with progressivenuclear palsy, dementia with Cortico-basal degeneration, mixed dementiawith Alzheimer's and vascular type, Alzheimer's disorder with difuseLewy Body disease, amyloid angiopathy, cerebral amyloid angiopathy,multi-infarct dementia, Down's syndrome, dementia associated withParkinson's disease, dementia of the Alzheimer's type, senile dementiaof the Alzheimer's type, vascular dementia, dementia due to HIV disease,dementia due to head trauma, dementia due to Huntington's disease,dementia due to Pick's disease, dementia due to Creutzfeldt-Jakobdisease, frontotemporal dementia, dementia pugilistica, dementiaassociated with beta-amyloid, amyloidosis of the brain and other organs(age and non-age related), Dutch type of hereditary cerebral haemorrhagewith amyloidosis, traumatic brain injury (TBI), temporal lobe epilepsy(TLE), hypoxia, ischemia, disruptions in cerebral metabolism,age-related macular degeneration, type 2 diabetes and other metabolicdisorders, amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS),arterial thrombosis, autoimmune/inflammatory diseases, cancer such asbreast cancer, cardiovascular diseases such as myocardial infarction andstroke, hypertension, dermatomyositis, prion disease (Creutzfeld-Jakobdisease), gastrointestinal diseases, Glioblastoma multiforme, Graves'Disease, Huntington's Disease, inclusion body myositis (IBM),inflammatory reactions, Kaposi Sarcoma, Kostmann Disease, lupuserythematosus, macrophagic myofasctitis, juvenile idiopathic arthritis,granulomatous arthritis, malignant melanoma, multiple myeloma,rheumatoid arthritis, Sjogren syndrome, SpinoCerebellar Ataxia 1,SpinoCerebellar Ataxia 7, Whippel's Disease and Wilson's Disease.

As used herein, the term “treatment” is intended to refer to allprocesses, wherein there may be a slowing, interrupting, arresting orstopping of the progression of a disease or an alleviation of symptoms,but does not necessarily indicate a total elimination of all symptoms.

The invention relates to a compound according to the general Formula(I), a stereoisomeric form thereof or a pharmaceutically acceptable acidor base addition salt thereof, for use as a medicament.

The invention also relates to a compound according to the generalFormula (I), a stereoisomeric form thereof or a the pharmaceuticallyacceptable acid or base addition salt thereof, for use in the treatmentor prevention of diseases or conditions selected from the groupconsisting of Alzheimer's Disease (AD), mild cognitive impairment (MCI),memory impairment, senility, dementia, dementia with Lewy bodies,dementia with progressive nuclear palsy, dementia with Cortico-basaldegeneration, mixed dementia with Alzheimer's and vascular type,Alzheimer's disorder with difuse Lewy Body disease, amyloid angiopathy,cerebral amyloid angiopathy, multi-infarct dementia, Down's syndrome,dementia associated with Parkinson's disease, dementia of theAlzheimer's type, senile dementia of the Alzheimer's type, vasculardementia, dementia due to HIV disease, dementia due to head trauma,dementia due to Huntington's disease, dementia due to Pick's disease,dementia due to Creutzfeldt-Jakob disease, frontotemporal dementia,dementia pugilistica, dementia associated with beta-amyloid, amyloidosisof the brain and other organs (age and non-age related), Dutch type ofhereditary cerebral haemorrhage with amyloidosis, traumatic brain injury(TBI), temporal lobe epilepsy (TLE), hypoxia, ischemia, disruptions incerebral metabolism, age-related macular degeneration, type 2 diabetesand other metabolic disorders, amyotrophic lateral sclerosis (ALS),multiple sclerosis (MS), arterial thrombosis, autoimmune/inflammatorydiseases, cancer such as breast cancer, cardiovascular diseases such asmyocardial infarction and stroke, hypertension, dermatomyositis, priondisease (Creutzfeld-Jakob disease), gastrointestinal diseases,Glioblastoma multiforme, Graves' Disease, Huntington's Disease,inclusion body myositis (IBM), inflammatory reactions, Kaposi Sarcoma,Kostmann Disease, lupus erythematosus, macrophagic myofasctitis,juvenile idiopathic arthritis, granulomatous arthritis, malignantmelanoma, multiple myeloma, rheumatoid arthritis, Sjogren syndrome,SpinoCerebellar Ataxia 1, SpinoCerebellar Ataxia 7, Whippel's Diseaseand Wilson's Disease; in particular AD, MCI, senility, dementia,dementia with Lewy bodies, cerebral amyloid angiopathy, multi-infarctdementia, Down's syndrome, dementia associated with Parkinson's disease,dementia of the Alzheimer's type and dementia associated withbeta-amyloid.

A skilled person will be familiar with alternative nomenclatures,nosologies, and classification systems for the diseases or conditionsreferred to herein. For example, the fifth edition of the Diagnostic &Statistical Manual of Mental Disorders (DSM-5™) of the AmericanPsychiatric Association utilizes terms such as neurocognitive disorders(NCDs) (both major and mild), in particular, neurocognitive disordersdue to Alzheimer's disease, due to traumatic brain injury (TBI), due toLewy body disease, due to Parkinson's disease or to vascular NCD (suchas vascular NCD present with multiple infarctions). Such terms may beused as an alternative nomenclature for some of the diseases orconditions referred to herein by the skilled person.

The invention also relates to the use of a compound according to thegeneral Formula (I), a stereoisomeric form thereof or a pharmaceuticallyacceptable acid or base addition salt thereof, for the manufacture of amedicament for the treatment or prevention of any one of the diseaseconditions mentioned hereinbefore.

The invention also relates to a compound according to the generalFormula (I), a stereoisomeric form thereof or a the pharmaceuticallyacceptable acid or base addition salt thereof, for use in the treatment,prevention, amelioration, control or reduction of the risk of diseasesor conditions selected from the group consisting of Alzheimer's Disease(AD), mild cognitive impairment (MCI), memory impairment, senility,dementia, dementia with Lewy bodies, dementia with progressive nuclearpalsy, dementia with Cortico-basal degeneration, mixed dementia withAlzheimer's and vascular type, Alzheimer's disorder with difuse LewyBody disease, amyloid angiopathy, cerebral amyloid angiopathy,multi-infarct dementia, Down's syndrome, dementia associated withParkinson's disease, dementia of the Alzheimer's type, senile dementiaof the Alzheimer's type, vascular dementia, dementia due to HIV disease,dementia due to head trauma, dementia due to Huntington's disease,dementia due to Pick's disease, dementia due to Creutzfeldt-Jakobdisease, frontotemporal dementia, dementia pugilistica, dementiaassociated with beta-amyloid, amyloidosis of the brain and other organs(age and non-age related), Dutch type of hereditary cerebral haemorrhagewith amyloidosis, traumatic brain injury (TBI), temporal lobe epilepsy(TLE), hypoxia, ischemia, disruptions in cerebral metabolism,age-related macular degeneration, type 2 diabetes and other metabolicdisorders, amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS),arterial thrombosis, autoimmune/inflammatory diseases, cancer such asbreast cancer, cardiovascular diseases such as myocardial infarction andstroke, hypertension, dermatomyositis, prion disease (Creutzfeld-Jakobdisease), gastrointestinal diseases, Glioblastoma multiforme, Graves'Disease, Huntington's Disease, inclusion body myositis (IBM),inflammatory reactions, Kaposi Sarcoma, Kostmann Disease, lupuserythematosus, macrophagic myofasctitis, juvenile idiopathic arthritis,granulomatous arthritis, malignant melanoma, multiple myeloma,rheumatoid arthritis, Sjogren syndrome, SpinoCerebellar Ataxia 1,SpinoCerebellar Ataxia 7, Whippel's Disease and Wilson's Disease; inparticular AD, MCI, senility, dementia, dementia with Lewy bodies,cerebral amyloid angiopathy, multi-infarct dementia, Down's syndrome,dementia associated with Parkinson's disease, dementia of theAlzheimer's type and dementia associated with beta-amyloid; or for usein the treatment, prevention, amelioration, control or reduction of therisk of diseases or conditions selected from neurocognitive disordersdue to Alzheimer's disease, due to traumatic brain injury (TBI), due toLewy body disease, due to Parkinson's disease or to vascular NCD (suchas vascular NCD present with multiple infarctions).

As already mentioned hereinabove, the term “treatment” does notnecessarily indicate a total elimination of all symptoms, but may alsorefer to symptomatic treatment in any of the disorders mentioned above.In view of the utility of the compound of Formula (I), there is provideda method of treating subjects such as warm-blooded animals, includinghumans, suffering from or a method of preventing subjects such aswarm-blooded animals, including humans, suffering from any one of thediseases mentioned hereinbefore.

Said methods comprise the administration, i.e. the systemic or topicaladministration, preferably oral administration, of a therapeuticallyeffective amount of a compound of Formula (I), a stereoisomeric formthereof, a pharmaceutically acceptable addition salt or solvate thereof,to a subject such as a warm-blooded animal, including a human.

Therefore, the invention also relates to a method for the preventionand/or treatment of any of the diseases mentioned hereinbeforecomprising administering a therapeutically effective amount of acompound according to the invention to a subject in need thereof.

A method of treatment may also include administering the activeingredient on a regimen of between one and four intakes per day. Inthese methods of treatment the compounds according to the invention arepreferably formulated prior to administration. As described hereinbelow, suitable pharmaceutical formulations are prepared by knownprocedures using well known and readily available ingredients.

The compounds of the present invention, that can be suitable to treat orprevent Alzheimer's disease (or by alternative nomenclatures, dementiaof the Alzheimer's type, or neurocognitive disorder due to Alzheimer'sdisease) or the symptoms thereof, may be administered alone or incombination with one or more additional therapeutic agents. Combinationtherapy includes administration of a single pharmaceutical dosageformulation which contains a compound of Formula (I) and one or moreadditional therapeutic agents, as well as administration of the compoundof Formula (I) and each additional therapeutic agents in its ownseparate pharmaceutical dosage formulation. For example, a compound ofFormula (I) and a therapeutic agent may be administered to the patienttogether in a single oral dosage composition such as a tablet orcapsule, or each agent may be administered in separate oral dosageformulations.

Pharmaceutical Compositions

The present invention also provides compositions for preventing ortreating diseases in which inhibition of beta-secretase is beneficial,such as Alzheimer's Disease (AD), mild cognitive impairment (MCI),memory impairment, senility, dementia, dementia with Lewy bodies,dementia with progressive nuclear palsy, dementia with Cortico-basaldegeneration, mixed dementia with Alzheimer's and vascular type,Alzheimer's disorder with difuse Lewy Body disease, amyloid angiopathy,cerebral amyloid angiopathy, multi-infarct dementia, Down's syndrome,dementia associated with Parkinson's disease, dementia of theAlzheimer's type, senile dementia of the Alzheimer's type, vasculardementia, dementia due to HIV disease, dementia due to head trauma,dementia due to Huntington's disease, dementia due to Pick's disease,dementia due to Creutzfeldt-Jakob disease, frontotemporal dementia,dementia pugilistica, dementia associated with beta-amyloid, amyloidosisof the brain and other organs (age and non-age related), Dutch type ofhereditary cerebral haemorrhage with amyloidosis, traumatic brain injury(TBI), temporal lobe epilepsy (TLE), hypoxia, ischemia, disruptions incerebral metabolism, age-related macular degeneration, type 2 diabetesand other metabolic disorders, amyotrophic lateral sclerosis (ALS),multiple sclerosis (MS), arterial thrombosis, autoimmune/inflammatorydiseases, cancer such as breast cancer, cardiovascular diseases such asmyocardial infarction and stroke, hypertension, dermatomyositis, priondisease (Creutzfeld-Jakob disease), gastrointestinal diseases,Glioblastoma multiforme, Graves' Disease, Huntington's Disease,inclusion body myositis (IBM), inflammatory reactions, Kaposi Sarcoma,Kostmann Disease, lupus erythematosus, macrophagic myofasctitis,juvenile idiopathic arthritis, granulomatous arthritis, malignantmelanoma, multiple myeloma, rheumatoid arthritis, Sjogren syndrome,SpinoCerebellar Ataxia 1, SpinoCerebellar Ataxia 7, Whippel's Diseaseand Wilson's Disease; in particular Alzheimer's disease (AD), mildcognitive impairment, senility, dementia, dementia with Lewy bodies,Down's syndrome, dementia associated with stroke, dementia associatedwith Parkinson's disease, dementia of the Alzheimer's type and dementiaassociated with beta-amyloid. According to alternative nomenclatures,the present invention provides compositions for preventing or treatingdiseases in which inhibition of beta-secretase is beneficial, such asneurocognitive disorders due to Alzheimer's disease, due to traumaticbrain injury (TBI), due to Lewy body disease, due to Parkinson's diseaseor to vascular NCD (such as vascular NCD present with multipleinfarctions). Said compositions comprising a therapeutically effectiveamount of a compound according to formula (I) and a pharmaceuticallyacceptable carrier or diluent.

While it is possible for the active ingredient to be administered alone,it is preferable to present it as a pharmaceutical composition.Accordingly, the present invention further provides a pharmaceuticalcomposition comprising a compound according to the present invention,together with a pharmaceutically acceptable carrier or diluent. Thecarrier or diluent must be “acceptable” in the sense of being compatiblewith the other ingredients of the composition and not deleterious to therecipients thereof.

The pharmaceutical compositions of this invention may be prepared by anymethods well known in the art of pharmacy. A therapeutically effectiveamount of the particular compound, in base form or addition salt form,as the active ingredient is combined in intimate admixture with apharmaceutically acceptable carrier, which may take a wide variety offorms depending on the form of preparation desired for administration.These pharmaceutical compositions are desirably in unitary dosage formsuitable, preferably, for systemic administration such as oral,percutaneous or parenteral administration; or topical administrationsuch as via inhalation, a nose spray, eye drops or via a cream, gel,shampoo or the like. For example, in preparing the compositions in oraldosage form, any of the usual pharmaceutical media may be employed, suchas, for example, water, glycols, oils, alcohols and the like in the caseof oral liquid preparations such as suspensions, syrups, elixirs andsolutions: or solid carriers such as starches, sugars, kaolin,lubricants, binders, disintegrating agents and the like in the case ofpowders, pills, capsules and tablets. Because of their ease inadministration, tablets and capsules represent the most advantageousoral dosage unit form, in which case solid pharmaceutical carriers areobviously employed. For parenteral compositions, the carrier willusually comprise sterile water, at least in large part, though otheringredients, for example, to aid solubility, may be included. Injectablesolutions, for example, may be prepared in which the carrier comprisessaline solution, glucose solution or a mixture of saline and glucosesolution. Injectable suspensions may also be prepared in which caseappropriate liquid carriers, suspending agents and the like may beemployed. In the compositions suitable for percutaneous administration,the carrier optionally comprises a penetration enhancing agent and/or asuitable wettable agent, optionally combined with suitable additives ofany nature in minor proportions, which additives do not cause anysignificant deleterious effects on the skin. Said additives mayfacilitate the administration to the skin and/or may be helpful forpreparing the desired compositions. These compositions may beadministered in various ways, e.g., as a transdermal patch, as a spot-onor as an ointment.

It is especially advantageous to formulate the aforementionedpharmaceutical compositions in dosage unit form for ease ofadministration and uniformity of dosage. Dosage unit form as used in thespecification and claims herein refers to physically discrete unitssuitable as unitary dosages, each unit containing a predeterminedquantity of active ingredient calculated to produce the desiredtherapeutic effect in association with the required pharmaceuticalcarrier. Examples of such dosage unit forms are tablets (includingscored or coated tablets), capsules, pills, powder packets, wafers,injectable solutions or suspensions, teaspoonfuls, tablespoonfuls andthe like, and segregated multiples thereof.

The exact dosage and frequency of administration depends on theparticular compound of formula (I) used, the particular condition beingtreated, the severity of the condition being treated, the age, weight,sex, extent of disorder and general physical condition of the particularpatient as well as other medication the individual may be taking, as iswell known to those skilled in the art. Furthermore, it is evident thatsaid effective daily amount may be lowered or increased depending on theresponse of the treated subject and/or depending on the evaluation ofthe physician prescribing the compounds of the instant invention.

Depending on the mode of administration, the pharmaceutical compositionwill comprise from 0.05 to 99% by weight, preferably from 0.1 to 70% byweight, more preferably from 0.1 to 50% by weight of the activeingredient, and, from 1 to 99.95% by weight, preferably from 30 to 99.9%by weight, more preferably from 50 to 99.9% by weight of apharmaceutically acceptable carrier, all percentages being based on thetotal weight of the composition.

The present compounds can be used for systemic administration such asoral, percutaneous or parenteral administration; or topicaladministration such as via inhalation, a nose spray, eye drops or via acream, gel, shampoo or the like. The compounds are preferably orallyadministered. The exact dosage and frequency of administration dependson the particular compound according to formula (I) used, the particularcondition being treated, the severity of the condition being treated,the age, weight, sex, extent of disorder and general physical conditionof the particular patient as well as other medication the individual maybe taking, as is well known to those skilled in the art. Furthermore, itis evident that said effective daily amount may be lowered or increaseddepending on the response of the treated subject and/or depending on theevaluation of the physician prescribing the compounds of the instantinvention.

The amount of a compound of Formula (I) that can be combined with acarrier material to produce a single dosage form will vary dependingupon the disease treated, the mammalian species, and the particular modeof administration. However, as a general guide, suitable unit doses forthe compounds of the present invention can, for example, preferablycontain between 0.1 mg to about 1000 mg of the active compound. Apreferred unit dose is between 1 mg to about 500 mg. A more preferredunit dose is between 1 mg to about 300 mg. Even more preferred unit doseis between 1 mg to about 100 mg. Such unit doses can be administeredmore than once a day, for example, 2, 3, 4, 5 or 6 times a day, butpreferably 1 or 2 times per day, so that the total dosage for a 70 kgadult is in the range of 0.001 to about 15 mg per kg weight of subjectper administration. A preferred dosage is 0.01 to about 1.5 mg per kgweight of subject per administration, and such therapy can extend for anumber of weeks or months, and in some cases, years. It will beunderstood, however, that the specific dose level for any particularpatient will depend on a variety of factors including the activity ofthe specific compound employed; the age, body weight, general health,sex and diet of the individual being treated; the time and route ofadministration; the rate of excretion; other drugs that have previouslybeen administered; and the severity of the particular disease undergoingtherapy, as is well understood by those of skill in the area.

A typical dosage can be one 1 mg to about 100 mg tablet or 1 mg to about300 mg taken once a day, or, multiple times per day, or one time-releasecapsule or tablet taken once a day and containing a proportionallyhigher content of active ingredient. The time-release effect can beobtained by capsule materials that dissolve at different pH values, bycapsules that release slowly by osmotic pressure, or by any other knownmeans of controlled release.

It can be necessary to use dosages outside these ranges in some cases aswill be apparent to those skilled in the art. Further, it is noted thatthe clinician or treating physician will know how and when to start,interrupt, adjust, or terminate therapy in conjunction with individualpatient response.

For the compositions and methods provided above, one of skill in the artwill understand that preferred compounds for use in each are thosecompounds that are noted as preferred above. Still further preferredcompounds for the compositions and methods are those compounds providedin the examples below.

EXPERIMENTAL PART

The following examples are intended to illustrate but not to limit thescope of the present invention.

Chemistry

Several methods for preparing the compounds of this invention areillustrated in the following Examples. Unless otherwise noted, allstarting materials were obtained from commercial suppliers and usedwithout further purification.

Hereinafter, “CI” means chemical ionisation; “DAD” means diode-arraydetector; “DBU” means 1,8-diazabicyclo(5.4.0)undec-7-ene; “DCM” meansdichloromethane; “DIPE” means diisopropylether; “DMF” meansN,N-dimethylformamide; “DMSO” means dimethylsulfoxide; “Et₂O” meansdiethylether; “EtOAc” means ethyl acetate; “EtOH” means ethanol; “ES”means electrospray; “h” means hours; “L” means liter; “LRMS” meanslow-resolution mass spectrometry/spectra; “HPLC” means high performanceliquid chromatography; “HRMS” means high-resolution massspectra/spectrometry; “MeOH” means methanol; “NH₄Ac” means ammoniumacetate; “eq” means equivalent; “RP” means Reversed Phase; “rt” meansroom temperature; “M.p.” means melting point; “min” means minutes; “s”means second(s); “TOF” means time of flight; “sat.” means saturated;“SFC” means supercritical fluid chromatography; “sol.” means solution,“TEA” means triethylamine; “THF” means tetrahydrofuran.

Thin layer chromatography (TLC) was carried out on silica gel 60 F254plates (Merck) using reagent grade solvents. Open column chromatographywas performed on silica gel, particle size 60 Å, mesh=230-400 (Merck)using standard techniques. Automated flash column chromatography normalphase was performed using Biotage® isolera™ 4 or Biotage® SP-1.Automated flash column chromatography reversed phase was performed using(a) a GILSON® Semi-Preparative System, operated by Trilution® software,equipped with a Phenomenex Gemini® C18 100A column (100 mm long×30 mmI.D.; 5 μm particles) at 25° C., with a flow rate of 40 mL/min or (b) aGILSON® Semi-Preparative System, operated by Unipoint software, equippedwith a Phenomenex Gemini® C18 100A column (100 mm long×21.2 mm I.D.; 5μm particles) at 25° C., with a flow rate of 20 mL/min.

For key intermediates, as well as some final compounds, the absoluteconfiguration of chiral centers (indicated as R and/or S) wereestablished via comparison with samples of known configuration, or theuse of analytical techniques suitable for the determination of absoluteconfiguration, such as VCD (vibrational circular dichroism) or X-raycrystallography.

Synthesis of Intermediate Compounds Intermediate 1 (I-1)(R)-1-[2-(5-bromo-2-fluoro-phenyl)-2-tert-butoxycarbonylamino-propyl]-1H-imidazole-4,5-dicarboxylicacid 4-ethyl ester 5-methyl ester (I-1)

DBU (11.3 mL, 76 mmol) was added to a stirred sol. of(4R)-4-(5-bromo-2-fluorophenyl)-4-methyl-1,2,3-oxathiazolidine-3-carboxylicacid 2,2-dioxide 1,1-dimethylethyl ester [CAS 1398113-03-5] (18.7 g,45.6 mmol) and diethyl 1H-imidazole-4,5-dicarboxylate (8.06 g, 38.0mmol) in acetonitrile (190 mL) at rt. The mixture was stirred at 90° C.for 5 h. The mixture was diluted with DCM and washed with HCl 1N. Theorganic layer was separated, dried (MgSO₄), filtered and the solventevaporated in vacuo. The crude product was purified by flash columnchromatography (silica; EtOAc in hexane 0/100 to 40/60). The desiredfractions were collected and the solvents evaporated in vacuo to yieldintermediate I-1 (21.7 g, 88%).

Intermediate 2 (I-2)(R)-3-[2-(5-bromo-2-fluoro-phenyl)-2-tert-butoxycarbonylamino-propyl]-3H-imidazole-4-carboxylicacid methyl ester (I-2)

Intermediate compound I-2 was synthesized following a similar approachdescribed for intermediate I-1. Starting from ethyl1H-imidazole-4-carboxylate (393 mg, 2.8 mmol), intermediate compound I-2was obtained as a colorless oil (145 mg, 74% purity, 12%).

Intermediate 3 (I-3)(R)-1-[2-amino-2-(5-bromo-2-fluoro-phenyl)-propyl]-1H-imidazole-4,5-dicarboxylicacid 4-ethyl ester 5-methyl ester hydrochloride (I-3)

A 4M sol. of HCl in 1,4-dioxane (40.2 mL, 160.8 mmol) was added to asol. of intermediate compound I-1 (21.8 g, 40.2 mmol) in 1,4-dioxane (40mL). The mixture was stirred at 70° C. for 15 h. The solvent wasevaporated in vacuo. Toluene was added and the mixture was evaporated invacuo to yield intermediate I-3 (19.2 g, quant.) that was used in thenext step without further purification.

Intermediate 4 (I-4)(R)-3-[2-amino-2-(5-bromo-2-fluoro-phenyl)-propyl]-3H-imidazole-4-carboxylicacid methyl ester hydrochloride (I-4)

Intermediate compound I-4 was synthesized following a similar approachdescribed for intermediate I-3. Starting from intermediate compound I-2(145 mg, 0.31 mmol), intermediate I-4 was obtained (114 mg, quant.).

Intermediate 5 (I-5)(R)-6-(5-bromo-2-fluoro-phenyl)-6-methyl-8-oxo-5,6,7,8-tetrahydro-imidazo[1,5-a]pyrazine-1-carboxylicacid (I-5)

Sodium methoxide (30 wt. % in MeOH, 0.16 mL, 0.88 mmol) was added to astirred sol. of intermediate compound I-3 (254 mg, 0.53 mmol) in MeOH (5mL) at rt. The mixture was stirred at 55° C. for 18 h. Then, 1M NaOHsol. (0.53 mL, 0.53 mmol) was added. The mixture was stirred at rt for 2h. The solvent was evaporated in vacuo. The residue was treated with 1MHCl until pH 4. The solid was filtered to yield intermediate I-5 (195mg, quant.) that was used in the next step without further purification.

Intermediate 6 (I-6)(R)-6-(5-bromo-2-fluoro-phenyl)-6-methyl-6,7-dihydro-5H-imidazo[1,5-a]pyrazin-8-one(I-6)

Method 1:

Sodium methoxide (30 wt. % in MeOH, 0.16 mL, 0.88 mmol) was added to astirred sol. of intermediate compound I-4 (254 mg, 0.53 mmol) in MeOH (5mL) at rt. The mixture was stirred at 55° C. for 18 h. The solvent wasevaporated in vacuo. The residue was treated with sat. aq. NH₄Cl sol.and extracted with DCM. The organic layer was separated, dried (MgSO₄),filtered and the solvents evaporated in vacuo. The crude product waspurified by flash column chromatography (silica; DCM-MeOH (20:1, v/v) inDCM 0/100 to 70/30). The desired fractions were collected and thesolvents evaporated in vacuo to yield intermediate I-6 (125 mg, 65%) asan oil.

Method 2:

Intermediate compound I-5 (1.4 g, 3.8 mmol) was dissolved in DMSO (10mL) and the mixture was stirred at 170° C. for 2 h. The solvent wasevaporated in vacuo. The crude product was purified by flash columnchromatography (silica; DCM-MeOH (10:1, v/v) in DCM 0/100 to 50/50). Thedesired fractions were collected and the solvents evaporated in vacuo toyield intermediate I-6 (1.22 g, 99%).

Intermediate 7 (I-7)(R)-6-(5-bromo-2-fluoro-phenyl)-6-methyl-6,7-dihydro-5H-imidazo[1,5-a]pyrazine-8-thione(I-7)

Phosphorus pentasulfide (5.09 g, 11.46 mmol) was added to a sol. ofintermediate compound I-6 (1.86 g, 5.73 mmol) in pyridine (14 mL) andthe mixture was stirred at 100° C. for 16 h. The solvent was evaporatedin vacuo. The crude product was purified by flash column chromatography(silica; EtOAc in hexane 0/100 to 50/50). The desired fractions werecollected and the solvents evaporated in vacuo to yield intermediate I-7(1.95 g, quant.).

Intermediate 8 (I-8)(R)-6-(5-bromo-2-fluoro-phenyl)-2,6-dimethyl-8-methylsulfanyl-5,6-dihydro-imidazo[1,5-a]pyrazin-2-iumiodate (I-8)

Methyl iodide (0.32 mL, 5.2 mmol) was added to a mixture of intermediatecompound I-7 (1.95 g, 5.7 mmol) and potassium carbonate (1.58 g, 11.5mmol) in acetone (28 mL). The mixture was stirred at rt for 16 h. Themixture was diluted with H₂O and extracted with DCM. The organic layerwas separated, dried (MgSO₄), filtered and the solvents evaporated invacuo. The crude product was purified by flash column chromatography(silica; DCM-MeOH (10:1, v/v) in DCM 0/100 to 100/0). The desiredfractions were collected and the solvents evaporated in vacuo to yieldintermediate I-8 (429 mg, 15%).

Intermediate 9 (I-9)(R)-6-(5-bromo-2-fluoro-phenyl)-2,6-dimethyl-8-methylsulfanyl-5,6-dihydro-2H-imidazo[1,5-a]pyrazin-3-one(I-9)

1M NaOH sol. (1.6 mL, 1.6 mmol) was added dropwise to a sol. ofintermediate compound I-8 (429 mg, 0.9 mmol) in THF (9 mL), followed bydropwise addition of sodium hypochlorite (1.57 mL) over 10 min at rt.The mixture was diluted with H₂O and extracted with EtOAc. The organiclayer was separated, dried (MgSO₄), filtered and the solvents evaporatedin vacuo to yield intermediate I-9 (332 mg, quant.) that was used in thenext step without further purification.

Intermediate 10 (I-10)(R)-8-amino-6-(5-bromo-2-fluoro-phenyl)-2,6-dimethyl-5,6-dihydro-2H-imidazo-[1,5-a]pyrazin-3-one(I-10)

Ammonium chloride (465 mg, 8.7 mmol) was added portionwise to a sol. ofintermediate compound I-9 (557 mg, 1.45 mmol) in 7 M sol. of ammonia inMeOH (5 mL) under nitrogen atmosphere. The mixture was stirred at 80° C.for 48 h. 7 M sol. of ammonia in MeOH (5 mL) and ammonium chloride (465mg, 8.7 mmol) were added and the mixture was stirred at 80° C. for 48 h.DCM and asat. aq. NaHCO₃ sol. were added. The organic phase wasseparated, dried (MgSO₄), filtered and the solvents evaporated in vacuo.The crude product was purified by flash column chromatography (silica;DCM-MeOH (10:1 (25% NH₃), v/v) in DCM 0/100 to 100/0). The desiredfractions were collected and the solvents evaporated in vacuo to yieldintermediate I-10 (385 mg, quant.).

Intermediate 11 (I-11)(R)-8-amino-6-(5-amino-2-fluoro-phenyl)-2,6-dimethyl-5,6-dihydro-2H-imidazo[1,5-a]pyrazin-3-one(I-11)

Sodium azide (78 mg, 1.2 mmol), copper (I) iodide (238 mg, 1.25 mmol)and Na₂CO₃ (212 mg, 2 mmol) were added to a sol. of intermediatecompound I-10 (354 mg, 1 mmol) in dry DMSO (10 mL). After the mixturewas well degassed, N,N′-dimethyl-ethylenediamine (0.19 mL, 1.75 mmol)was added. The mixture was stirred at 110° C. for 4 h. The mixture wasdiluted with NH₃ sol. The solvents were evaporated in vacuo. The crudeproduct was purified by flash column chromatography (silica; DCM-MeOH(10:1, v/v) in DCM 0/100 to 100/0). The desired fractions were collectedand the solvents evaporated in vacuo to yield intermediate I-11 (310 mg,93% purity, quant.).

Intermediate 12 (I-12)

Methyl iodide (5.12 mL, 82.2 mmol) was added to a mixture ofintermediate compound I-7 (10.72 g, 27.41 mmol) and 6M aq. sodiumhydroxide solution (9.1 mL, 54.83 mmol) in EtOH (82 mL). The mixture wasstirred at rt for 6 h. Extra methyl iodide (1.7 mL, 27.3 mmol) wasadded. The mixture was stirred at rt for 15 h. The mixture was dilutedwith H₂O and extracted with DCM. The organic layer was separated, dried(MgSO₄), filtered and the solvents evaporated in vacuo. The crudeproduct was purified by flash column chromatography (silica;EtOAc/heptanes 0/100 to 30/70). The desired fractions were collected andconcentrated in vacuo to yield intermediate I-12 (6.2 g, 64%).

Intermediate 13 (I-13)

2,2,2-Trifluoroethyl perfluorobutylsulfonate (1.2 mL, 5308 mmol) wasadded dropwise to a stirred sol. of intermediate I-12 (1.5 g, 4.23 mmol)in acetonitrile (15 mL) at rt. The mixture was stirred at 60° C. for 16h. Extra 2,2,2-trifluoroethyl perfluorobutylsulfonate (0.3 mL, 1.27mmol) was added and the reaction mixture was stirred at 60° C. for 5 h.The rm was diluted with water and extracted with DCM. The organic layerwas separated, dried (MgSO₄), filtered and the solvents evaporated invacuo. The crude product was purified by flash column chromatography(silica; EtOAc (10:1, v/v) in DCM 0/100 to 80/20). The desired fractionswere collected and concentrated in vacuo to yield intermediate I-13 (2.1g, 67%).

Intermediate 14 (I-14)

5% Sodium hypochlorite aq. solution (43 mL) was added dropwise to asolution of intermediate I-13 (2.1 g, 2.85 mmol) in THF (45 mL) at 0° C.The mixture was stirred at RT for 30 min. The rm was diluted with waterand extracted with EtOAc. The organic layer was separated, dried(MgSO₄), filtered and the solvents evaporated in vacuo to yieldintermediate I-14 (1.38 g, 100%), which was used without furtherpurification in the next reaction step.

Intermediate 15 (I-15)

Intermediate compound I-15 was synthesized following a similar approachdescribed for intermediate I-10. Starting from intermediate compoundI-14 (1.38 g, 2.85 mmol), intermediate I-15 was obtained (0.69 g, 57%).

Intermediate 16 (I-16)

Intermediate compound I-16 was synthesized following a similar approachdescribed for intermediate I-11. Starting from intermediate compoundI-15 (0.693 g, 1.65 mmol), intermediate I-16 was obtained (0.345 mg,58%).

Final Compounds

Example 1N-{3-[(6R)-8-Amino-2,6-dimethyl-3-oxo-2,3,5,6-tetrahydroimidazo[1,5-a]pyrazin-6-yl]-4-fluorophenyl}-5-cyanopyridine-2-carboxamide(compound 1)

5-Cyano-2-pyridine carboxylic acid (118 mg, 0.8 mmol) was added to astirred sol. of4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (257mg, 0.87 mmol) in MeOH (7 mL). After 5 min, intermediate compound I-11(216 mg, 0.83 mmol) in MeOH (2 mL) was added at 0° C. The mixture wasstirred at rt for 24 h. The mixture was treated with asat. aq. Na₂CO₃sol. and extracted with DCM. The organic phase was separated, dried(MgSO₄), filtered and the solvents evaporated in vacuo. The crudeproduct was purified by flash column chromatography (silica; DCM-MeOH(10:1(25% NH₃), v/v) in DCM 0/100 to 100/0). The desired fractions werecollected and the solvents evaporated in vacuo. The solid was trituratedwith Et₂O and filtered to yield compound 1 as a solid (48 mg, 15%).

Example 2(6R)-8-Amino-6-(2-fluoro-5-pyrimidin-5-ylphenyl)-2,6-dimethyl-5,6-dihydro-imidazo[1,5-a]pyrazin-3(2H)-one(compound 2)

A sol. of intermediate compound I-10 (92 mg, 0.26 mmol),pyrimidine-5-boronic acid (35 mg, 0.29 mmol) and 1M Na₂CO₃ sol. (0.52mL, 0.52 mmol) in 1,4-dioxane (3 mL) was degassed with nitrogen for 5min. Then, 1,1′-bis(diphenylphosphino)-ferrocene-palladium(II)dichloridedichloromethane complex (11 mg, 0.013 mmol) was added. The mixture wasstirred for 4 h at 100° C. H₂O and EtOAc were added. The organic phasewas separated, dried (MgSO₄), filtered and the solvents evaporated invacuo. The crude product was purified by flash column chromatography(silica; DCM-MeOH (10:1(25% NH₃), v/v) in DCM 0/100 to 80/20). Thedesired fractions were collected and the solvents evaporated in vacuo.Then the product was purified by RP HPLC using as mobile phase (95% H₂O(25 mM NH₄HCO₃)-5% CH₃CN—MeOH to 0% H₂O (25 mM NH₄HCO3)-100%CH₃CN—MeOH). The desired fractions were collected and the solventsevaporated in vacuo. The product was triturated with DIPE to yieldcompound 2 as a white solid (17 mg, 18%).

Example 3N-{3-[(6R)-8-amino-6-methyl-3-oxo-2-(2,2,2-trifluoroethyl)-2,3,5,6-tetrahydroimidazo[1,5-a]pyrazin-6-yl]-4-fluorophenyl}-5-chloropyridine-2-carboxamide(compound 8)

5-Chloro-2-pyridine carboxylic acid (48.5 mg, 0.31 mmol) was added to astirred sol. of4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (155mg, 0.34 mmol) in MeOH (10 mL). After 5 min, intermediate compound I-16(100 mg, 0.28 mmol) in MeOH (5 mL) was added at 0° C. The mixture wasstirred at rt for 16 h. The mixture was treated with sat. aq. Na₂CO₃sol. and extracted with DCM. The organic phase was separated, dried(MgSO₄), filtered and the solvents evaporated in vacuo. The crudeproduct was purified by flash column chromatography (silica; DCM-MeOH(10:1(25% NH₃), v/v) in DCM 0/100 to 40/60). The desired fractions werecollected and the solvents evaporated in vacuo. The solid was trituratedwith DIPE and filtered to yield compound 8 as a solid (69 mg, 50%).

Table 1 below lists additional compounds of Formula (I).

TABLE 1 The following compounds were prepared following the methodsexemplified in the Experimental Part (Ex. No.).

Co. Ex. No. No. R¹ R R² R³ R⁴ 1 E1* H Me Me (R) a-F

2 E2* H Me Me (R) a-F

3 E1 H Me Me (R) a-F

4 E1 H Me Me (R) a-F

5 E1 H Me Me (R) a-F

6 E1 H Me Me (R) a-F

7 E3 H CH₂CF₃ Me (R) a-F

8 E3* H CH₂CF₃ Me (R) a-F

9 E1 H Me Me (R) a-F

10 E3 H CH₂CF₃ Me (R) a-F

11 E3 H CH₂CF₃ Me (R) a-F

Compounds exemplified and described in the experimental part are markedwith an asterisk *.Analytical PartMelting Points (mp)

Values are either peak values or melt ranges, and are obtained withexperimental uncertainties that are commonly associated with thisanalytical method.

For a number of compounds, melting points were determined in opencapillary tubes on a Mettler Toledo MP50 apparatus or on a MettlerToledo EP 62 (indicated as (a) in table 2b below). Melting points weremeasured with a temperature gradient of 10° C./minute. Maximumtemperature was 300° C. The melting point was read from a digitaldisplay.

LCMS

For (LC)MS-characterization of the compounds of the present invention,the following methods were used.

The High Performance Liquid Chromatography (HPLC) measurement wasperformed using a LC pump, a diode-array (DAD) or a UV detector and acolumn as specified in the respective methods. If necessary, additionaldetectors were included (see table of methods 2a below).

Flow from the column was brought to the Mass Spectrometer (MS) which wasconfigured with an atmospheric pressure ion source. It is within theknowledge of the skilled person to set the tune parameters (e.g.scanning range, dwell time . . . ) in order to obtain ions allowing theidentification of the compound's nominal monoisotopic molecular weight(MW). Data acquisition was performed with appropriate software.Compounds are described by their experimental retention times (R_(t))and ions. If not specified differently in the table of data, thereported molecular ion corresponds to the [M+H]⁺ (protonated molecule)and/or [M−H]⁻ (deprotonated molecule). In case the compound was notdirectly ionizable the type of adduct is specified (i.e. [M+NH₄]⁺,[M+HCOO]⁻, etc. . . . ). For molecules with multiple isotopic patterns(Br, Cl . . . ), the reported value is the one obtained for the lowestisotope mass. All results were obtained with experimental uncertaintiesthat are commonly associated with the method used.

Hereinafter, “SQD” means Single Quadrupole Detector, “MSD” MassSelective Detector, “RT” room temperature, “BEH” bridgedethylsiloxane/silica hybrid, “DAD” Diode Array Detector, “HSS” HighStrength silica., “Q-Tof” Quadrupole Time-of-flight mass spectrometers,“CLND”, ChemiLuminescent Nitrogen Detector, “ELSD” Evaporative LightScanning Detector.

TABLE 2a LCMS Method codes (Flow expressed in mL/min; column temperature(T) in ° C.; Run time in minutes). Method code Instrument Column Mobilephase Gradient $\frac{Flow}{{Col}\mspace{14mu} T}$ Run time 1 Agilent1100- DAD- YMC- pack ODS-AQ A: 0.1% HCOOH in H₂O From 95% A to 5% A in4.8 min, $\frac{2.6}{35}$ 6.0 MSD C18 (50 × B: CH₃CN held for G1956A 4.6mm, 1.0 min, to 3 μm) 95% A in 0.2 min.

TABLE 2b Analytical data-melting point (M.p.) and LCMS: [M + H]⁺ meansthe protonated mass of the free base of the compound, R_(t) meansretention time (in min), method refers to the method used for LCMS. M.p.LCMS No. (° C.) [M + H]⁺ R_(t) Method 1 270.0 420 1.864 1 2 239.1 3530.416 1 3 224.9 399 1.621 1 4   214.8 (a) 429 2.084 1 5 n.d. 426 1.836 16 n.d. 413 1.702 1 7 239.9 481 1.999 1 8 219.9 497 2.113 1 9 n.d. 4341.763 1 10 235.0 488 1.969 1 11 280.5 494 1.995 1 n.d. means notdetermined¹H NMR

For a number of compounds, ¹H NMR spectra were recorded on a Bruker 300MHz Ultrashield with standard pulse sequences, operating at 300 MHzusing CHLOROFORM-d (deuterated chloroform, CDCl₃) or DMSO-d₆ (deuteratedDMSO, dimethyl-d6 sulfoxide) as solvent. Chemical shifts (δ) arereported in parts per million (ppm) relative to tetramethylsilane (TMS),which was used as internal standard.

TABLE 3 ¹H NMR results Co. No. ¹H NMR result 1 (300 MHz, DMSO-d₆) δ ppm1.49 (s, 3 H), 3.22 (s, 3 H), 3.66-3.91 (m, 2 H), 6.30 (br. s., 2 H),7.11 (s, 1 H), 7.25 (dd, J = 12.0, 8.9 Hz, 1 H), 7.81 (dt, J = 8.5, 3.5Hz, 1 H), 8.14 (dd, J = 7.4, 2.5 Hz, 1 H), 8.32 (d, J = 8.2 Hz, 1 H),8.64 (dd, J = 8.2, 2.0 Hz, 1 H), 9.15-9.35 (m, 1 H), 10.81 (s, 1 H). 2(300 MHz, DMSO-d₆) δ ppm 1.70 (br. s., 3 H), 3.26 (s, 3 H), 3.92 (d, J =12.9 Hz, 1 H), 4.36 (br. s., 1 H), 7.40-7.63 (m, 2 H), 7.81-7.99 (m, 2H), 9.13 (s, 2 H), 9.27 (s, 1 H). 3 (300 MHz, DMSO-d₆) δ ppm 1.48 (s, 3H), 2.57 (s, 3 H), 3.22 (s, 3 H), 3.67-3.89 (m, 2 H), 6.24 (br. s., 2H), 7.10 (br. s., 1 H), 7.20 (dd, J = 12.0, 8.9 Hz, 1 H), 7.61-7.75 (m,1 H), 8.03 (dd, J = 7.6, 2.5 Hz, 1 H), 8.67 (s, 1 H), 10.11 (s, 1 H). 4(300 MHz, DMSO-d₆) δ ppm 1.42 (s, 3 H), 3.16 (s, 3 H), 3.69 (d, J = 12.5Hz, 1 H), 3.79 (d, J = 12.4 Hz, 1 H), 6.14 (br. s., 2 H), 7.02 (s, 1 H),7.18 (dd, J = 12.0, 8.8 Hz, 1 H), 7.75 (dt, J = 8.3, 3.5 Hz, 1 H), 8.06(dd, J = 7.3, 2.5 Hz, 1 H), 8.14 (d, J = 8.4 Hz, 1 H), 8.20 (dd, J =8.4, 2.1 Hz, 1 H), 8.79 (d, J = 2.1 Hz, 1 H), 10.57 (s, 1 H). 5 (300MHz, DMSO-d₆) δ ppm 1.41 (s, 3 H), 3.15 (s, 3 H), 3.61-3.83 (m, 2 H),4.02 (s, 3 H), 6.10 (br. s, 2 H), 7.00 (s, 1 H), 7.16 (dd, J = 12.05,8.76 Hz, 1 H), 7.66-7.75 (m, 1 H), 8.05 (dd, J = 7.20, 2.61 Hz, 1 H),8.40 (d, J = 1.28 Hz, 1 H), 8.87 (d, J = 1.34 Hz, 1 H), 10.39 (br. s, 1H). 6 (300 MHz, DMSO-d₆) δ ppm 1.41 (s, 3 H), 3.15 (s, 3 H), 3.66 (d, J= 12.10 Hz, 1 H), 3.79 (d, J = 12.10 Hz, 1 H), 6.10 (br. s., 2 H), 7.00(s, 1 H), 7.16 (dd, J = 11.95, 8.74 Hz, 1 H), 7.68-7.78 (m, 1 H), 7.97(td, J = 8.70, 2.86 Hz, 1 H), 8.05 (dd, J = 7.47, 2.58 Hz, 1 H), 8.21(dd, J = 8.71, 4.72 Hz, 1 H), 8.73 (d, J = 2.58 Hz 1 H) 10.49 (br s 1H). 7 (300 MHz, CHLOROFORM-d) δ ppm 1.64 (s, 3 H), 3.94-4.11 (m, 2 H),4.13-4.43 (m, 2 H), 7.02 (s, 1 H), 7.10 (dd, J = 11.58, 8.70 Hz, 1 H),7.59 (td, J = 8.33, 2.76 Hz, 1 H), 7.78-7.88 (m, 2 H), 8.32 (dd, J =8.73, 4.55 Hz, 1 H), 8.45 (d, J = 2.73 Hz, 1 H), 9.80 (s, 1 H). 8 (300MHz, DMSO-d₆) δ ppm 1.57 (br. s., 3 H), 3.77-3.94 (m, 1 H), 3.97-4.23(m, 1 H), 4.58 (q, J = 9.32 Hz, 2 H), 7.23 (dd, J = 12.15, 8.74 Hz, 1H), 7.49 (br. s, 1 H), 7.71-7.87 (m, 1 H), 8.00 (dd, J = 7.40, 2.20 Hz,1 H), 8.13 (d, J = 8.30 Hz, 1 H), 8.20 (dd, J = 8.40, 2.20 Hz, 1 H),8.78 (d, J = 2.32 Hz, 1 H), 10.70 (s, 1 H). 9 (300 MHz, CHLOROFORM-d) δppm 1.58 (s, 3 H), 2.86 (s, 3 H), 3.32 (s, 3 H), 3.87 (d, J = 12.78 Hz,1 H), 4.11 (d, J = 12.73 Hz, 1 H), 6.67 (s, 1 H), 7.09 (dd, J = 11.53,8.84 Hz, 1 H), 7.73 (dd, J = 6.98, 2.76 Hz, 1 H), 7.88-7.98 (m, 2 H),8.72 (d, J = 1.10 Hz, 1 H), 9.99 (s, 1 H). 10 (300 MHz, DMSO-d₆) δ ppm1.45 (s, 3 H), 3.60-4.15 (m, 2 H), 4.54 (q, J = 9.35 Hz, 2 H), 6.27 (br.s, 2 H), 7.10-7.28 (m, 2 H), 7.73-7.81 (m, 1 H), 8.03-8.12 (m, 1 H),8.22-8.31 (m, 1 H), 8.57 (dd, J = 8.18, 2.01 Hz, 1 H), 9.17-9.20 (m, 1H), 10.76 (s, 1 H). 11 (300 MHz, DMSO-d₆) δ ppm 1.45 (br. s., 3 H),3.63-3.94 (m, 2 H), 4.02 (s, 3 H), 4.47-4.60 (m, 2 H), 5.79-6.70 (m, 2H), 7.18 (m, J = 12.14, 8.70 Hz, 2 H), 7.70-7.77 (m, 1 H), 8.02-8.10 (m,1 H), 8.41 (d, J = 1.39 Hz, 1 H), 8.87 (d, J = 1.34 Hz, 1 H), 10.42 (br.s., 1 H).

PHARMACOLOGICAL EXAMPLES

The compounds provided in the present invention are inhibitors of thebeta-site APP-cleaving enzyme 1 (BACE1). Inhibition of BACE1, anaspartic protease, is believed to be relevant for treatment ofAlzheimer's Disease (AD). The production and accumulation ofbeta-amyloid peptides (Abeta) from the beta-amyloid precursor protein(APP) is believed to play a key role in the onset and progression of AD.Abeta is produced from the amyloid precursor protein (APP) by sequentialcleavage at the N- and C-termini of the Abeta domain by beta-secretaseand gamma-secretase, respectively.

Compounds of Formula (I) are expected to have their effect substantiallyat BACE1 by virtue of their ability to inhibit the enzymatic activity.The behaviour of such inhibitors tested using a biochemical FluorescenceResonance Energy Transfer (FRET) based assay and a cellular αLisa assayin SKNBE2 cells described below and which are suitable for theidentification of such compounds, and more particularly the compoundsaccording to Formula (I), are shown in Table 3 and Table 4.

BACE 1 Biochemical FRET Based Assay

This assay is a Fluorescence Resonance Energy Transfer Assay (FRET)based assay. The substrate for this assay is an APP derived 13 aminoacids peptide that contains the ‘Swedish’ Lys-Met/Asn-Leu mutation ofthe amyloid precursor protein (APP) beta-secretase cleavage site. Thissubstrate also contains two fluorophores: (7-methoxycoumarin-4-yl)acetic acid (Mca) is a fluorescent donor with excitation wavelength at320 nm and emission at 405 nm and 2,4-Dinitrophenyl (Dnp) is aproprietary quencher acceptor. The distance between those two groups hasbeen selected so that upon light excitation, the donor fluorescenceenergy is significantly quenched by the acceptor, through resonanceenergy transfer. Upon cleavage by BACE1, the fluorophore Mca isseparated from the quenching group Dnp, restoring the full fluorescenceyield of the donor. The increase in fluorescence is linearly related tothe rate of proteolysis.

Briefly in a 384-well format recombinant BACE1 protein in a finalconcentration of 0.04 μg/ml is incubated for 450 minutes at roomtemperature with 20 μM substrate in incubation buffer (50 mM Citratebuffer pH 5.0, 0.05% PEG) in the presence of compound or DMSO. Next theamount of proteolysis is directly measured by fluorescence measurement(excitation at 320 nm and emission at 405 nm) at different incubationtimes (0, 30, 60, 90, 120 and 450 min). For every experiment a timecurve (every 30 min between 0 min and 120 min) is used to determine thetime where we find the lowest basal signal of the high control. Thesignal at this time (Tx) is used to subtract from the signal at 450 min.Results are expressed in RFU, as difference between T450 and Tx.

A best-fit curve is fitted by a minimum sum of squares method to theplot of % Controlmin versus compound concentration. From this an IC₅₀value (inhibitory concentration causing 50% inhibition of activity) canbe obtained.

-   LC=Median of the low control values    -   =Low control: Reaction without enzyme-   HC=Median of the High control values    -   =High Control: Reaction with enzyme-   % Effect=100−[(sample−LC)/(HC−LC)*100]-   % Control=(sample/HC)*100-   % Controlmin=(sample−LC)/(HC−LC)*100

The following exemplified compounds were tested essentially as describedabove and exhibited the following the activity:

TABLE 4 Biochemical FRET Co. based assay No. pIC₅₀ 2 6.31 3 8.02 1 8.534 8.4 5 8.02 6 7.82 7 7.91 8 8.33 9 8.11 10 8.25 11 8.06Cellular αLisa Assay in SKNBE2 Cells

In two αLisa assays the levels of Abeta total and Abeta 1-42 producedand secreted into the medium of human neuroblastoma SKNBE2 cells arequantified. The assay is based on the human neuroblastoma SKNBE2expressing the wild type Amyloid Precursor Protein (hAPP695). Thecompounds are diluted and added to these cells, incubated for 18 hoursand then measurements of Abeta 1-42 and Abeta total are taken. Abetatotal and Abeta 1-42 are measured by sandwich αLisa. αLisa is a sandwichassay using biotinylated antibody AbN/25 attached to streptavidin coatedbeads and antibody Ab4G8 or cAb42/26 conjugated acceptor beads for thedetection of Abeta total and Abeta 1-42 respectively. In the presence ofAbeta total or Abeta 1-42, the beads come into close proximity. Theexcitation of the donor beads provokes the release of singlet oxygenmolecules that trigger a cascade of energy transfer in the acceptorbeads, resulting in light emission. Light emission is measured after 1hour incubation (excitation at 650 nm and emission at 615 nm).

A best-fit curve is fitted by a minimum sum of squares method to theplot of % Controlmin versus compound concentration. From this an IC₅₀value (inhibitory concentration causing 50% inhibition of activity) canbe obtained.

-   LC=Median of the low control values    -   =Low control: cells preincubated without compound, without        biotinylated Ab in the αLisa-   HC=Median of the High control values    -   =High Control: cells preincubated without compound-   % Effect=100−[(sample−LC)/(HC−LC)*100]-   % Control=(sample/HC)*100-   % Controlmin=(sample−LC)/(HC−LC)*100

The following exemplified compounds were tested essentially as describedabove and exhibited the following the activity:

TABLE 5 Cellular αLisa assay in Cellular αLisa assay in SKNBE2 cellsSKNBE2 cells Co. Abeta 42 Abetatotal No. pIC₅₀ pIC₅₀ 2 5.9 5.99 3 7.247.28 1 7.88 7.94 4 8.2 8.22 5 7.44 7.53 6 7.06 7.05 7 7.73 7.78 8 8.258.32 9 7.41 7.48 10 7.9 7.97 11 7.91 8BACE2 Biochemical FRET Based Assay

This assay is a Fluorescence Resonance Energy Transfer Assay (FRET)based assay. The substrate for this assay contains the ‘Swedish’Lys-Met/Asn-Leu mutation of the amyloid precursor protein (APP)beta-secretase cleavage site. This substrate also contains twofluorophores: (7-methoxycoumarin-4-yl) acetic acid (Mca) is afluorescent donor with excitation wavelength at 320 nm and emission at405 nm and 2,4-Dinitrophenyl (Dnp) is a proprietary quencher acceptor.The distance between those two groups has been selected so that uponlight excitation, the donor fluorescence energy is significantlyquenched by the acceptor, through resonance energy transfer. Uponcleavage by the beta-secretase, the fluorophore Mca is separated fromthe quenching group Dnp, restoring the full fluorescence yield of thedonor. The increase in fluorescence is linearly related to the rate ofproteolysis.

Briefly in a 384-well format recombinant BACE2 protein in a finalconcentration of 0.4 μg/ml is incubated for 450 minutes at roomtemperature with 10 μM substrate in incubation buffer (50 mM Citratebuffer pH 5.0, 0.05% PEG, no DMSO) in the absence or presence ofcompound. Next the amount of proteolysis is directly measured byfluorescence measurement at T=0 and T=450 (excitation at 320 nm andemission at 405 nm). Results are expressed in RFU (Relative FluorescenceUnits), as difference between T450 and T0.

A best-fit curve is fitted by a minimum sum of squares method to theplot of % Controlmin versus compound concentration. From this an IC₅₀value (inhibitory concentration causing 50% inhibition of activity) canbe obtained.

-   LC=Median of the low control values    -   =Low control: Reaction without enzyme-   HC=Median of the High control values    -   =High Control: Reaction with enzyme-   % Effect=100−[(sample−LC)/(HC−LC)*100]-   % Control=(sample/HC)*100-   % Controlmin=(sample−LC)/(HC−LC)*100

The following exemplified compounds were tested essentially as describedabove and exhibited the following the activity:

TABLE 6 BACE2 Biochemical Co. FRET based assay Nr. pIC₅₀ 1 7.71 2 5.15 38.18 4 8.36 5 7 6 7.88 7 8.13 8 8.18 9 7.64 10 7.92 11 7.26 n.t. meansnot testedDemonstration of in Vivo Efficacy

Aβ lowering agents of the invention can be used to treat AD in mammalssuch as humans or alternatively demonstrating efficacy in animal modelssuch as, but not limited to, the mouse, rat, or guinea pig. The mammalmay not be diagnosed with AD, or may not have a genetic predispositionfor AD, but may be transgenic such that it overproduces and eventuallydeposits Aβ in a manner similar to that seen in humans afflicted withAD.

Aβ lowering agents can be administered in any standard form using anystandard method. For example, but not limited to, Aβ lowering agents canbe in the form of liquid, tablets or capsules that are taken orally orby injection. Aβ lowering agents can be administered at any dose that issufficient to significantly reduce levels of Aβ in the blood, bloodplasma, serum, cerebrospinal fluid (CSF), or brain.

To determine whether acute administration of an Aβ lowering agent wouldreduce Aβ levels in vivo, non-transgenic rodents, e.g. mice or rats wereused. Animals treated with the Aβ lowering agent were examined andcompared to those untreated or treated with vehicle and brain levels ofsoluble Aβ42, Aβ40, Aβ38, and Aβ37 were quantitated by Meso ScaleDiscovery's (MSD) electrochemiluminescence detection technology.Treatment periods varied from hours (h) to days and were adjusted basedon the results of the Aβ lowering once a time course of onset of effectcould be established.

A typical protocol for measuring Aβ lowering in vivo is shown but it isonly one of many variations that could be used to optimize the levels ofdetectable Aβ. For example, Aβ lowering compounds were formulated in 20%of Captisol® (a sulfo-butyl ether of β-cyclodextrin) in water or 20%hydroxypropyl β cyclodextrin. The Aβ lowering agents were administeredas a single oral dose or by any acceptable route of administration toovernight fasted animals. After 4 h, the animals were sacrificed and Aβlevels were analysed.

Blood was collected by decapitation and exsanguinations in EDTA-treatedcollection tubes. Blood was centrifuged at 1900 g for 10 minutes (min)at 4° C. and the plasma recovered and flash frozen for later analysis.The brain was removed from the cranium and hindbrain. The cerebellum wasremoved and the left and right hemisphere were separated. The lefthemisphere was stored at −18° C. for quantitative analysis of testcompound levels. The right hemisphere was rinsed with phosphate-bufferedsaline (PBS) buffer and immediately frozen on dry ice and stored at −80°C. until homogenization for biochemical assays.

Mouse brains from non-transgenic animals were resuspended in 8 volumesof 0.4% DEA (diethylamine)/50 mM NaCl containing protease inhibitors(Roche-11873580001 or 04693159001) per gram of tissue, e.g. for 0.158 gbrain, add 1.264 ml of 0.4% DEA. All samples were homogenized in theFastPrep-24 system (MP Biomedicals) using lysing matrix D (MPBio#6913-100) at 6 m/s for 20 seconds. Homogenates were centrifuged at20800×g for 5 min and supernatants collected. Supernatants werecentrifuged at 221.300×g for 50 min. The resulting high speedsupernatants were then transferred to fresh eppendorf tubes. Nine partsof supernatant were neutralized with 1 part 0.5 M Tris-HCl pH 6.8 andused to quantify Aβ.

To quantify the amount of Aβ42, Aβ40, Aβ38, and Aβ37 in the solublefraction of the brain homogenates, simultaneous specific detection ofAβ42, Aβ40, Aβ38, and Aβ37 was performed using MSD'selectro-chemiluminescence multiplex detection technology. In this assaypurified monoclonal antibodies specific for Abeta37 (JRD/Aβ37/3),Abeta38 (J&JPRD/Aβ38/5), Abeta40 (JRF/cAβ40/28), and Abeta42(JRF/cAβ42/26) were coated on MSD 4-plex plates. Briefly, the standards(a dilution of synthetic Aβ42, Aβ40, Aβ38, and Aβ37) were prepared in1.5 ml Eppendorf tube in Ultraculture, with final concentrations rangingfrom 10000 to 0.3 pg/m. The samples and standards were co-incubated withSulfo-tag labelled JRF/rAβ/2 antibody to the N-terminus of Aβ asdetector antibody. 50 μl of conjugate/sample or conjugate/standardsmixtures were then added to the antibody-coated plate. The plate wasallowed to incubate overnight at 4° C. in order to allow formation ofthe antibody-amyloid complex. Following this incubation and subsequentwash steps the assay was finished by adding read buffer according to themanufacturer's instructions (Meso Scale Discovery, Gaitherburg, Md.).

The SULFO-TAG emits light upon electrochemical stimulation initiated atthe electrode. MSD Sector instrument SI6000 was used for signalread-out.

In this model a Aβ lowering compared to untreated animals would beadvantageous, in particular a Aβ lowering with at least 10%, more inparticular a Aβ lowering with at least 20%.

Results

The results are shown in Table 7 (value for untreated animals as control(Ctrl) was set at 100):

Co. Aβ40 (% vs Aβ42 (% vs Route of Time after No. Ctrl)_Mean Ctrl)_MeanDose administration administration 1 105 105 10 s.c. 2 h 1 132 109 10s.c. 4 h 3 94 97 10 p.o. 4 h 4 121 125 10 s.c. 4 h s.c. meanssubcutaneous; p.o. means oral

PROPHETIC COMPOSITION EXAMPLES

“Active ingredient” as used throughout these examples relates to a finalcompound of Formula (I), the pharmaceutically acceptable salts thereof,the solvates and the stereochemically isomeric forms thereof.

Typical examples of recipes for the formulation of the invention are asfollows:

1. Tablets

Active ingredient 5 to 50 mg Di-calcium phosphate 20 mg Lactose 30 mgTalcum 10 mg Magnesium stearate 5 mg Potato starch ad 200 mg

In this Example, active ingredient can be replaced with the same amountof any of the compounds according to the present invention, inparticular by the same amount of any of the exemplified compounds.

2. Suspension

An aqueous suspension is prepared for oral administration so that each 1milliliter contains 1 to 5 mg of one of the active compounds, 50 mg ofsodium carboxymethyl cellulose, 1 mg of sodium benzoate, 500 mg ofsorbitol and water ad 1 ml.

3. Injectable

A parenteral composition is prepared by stirring 1.5% by weight ofactive ingredient of the invention in 10% by volume propylene glycol inwater.

4. Ointment

Active ingredient 5 to 1000 mg Stearyl alcohol 3 g Lanoline 5 g Whitepetroleum 15 g Water ad 100 g

In this Example, active ingredient can be replaced with the same amountof any of the compounds according to the present invention, inparticular by the same amount of any of the exemplified compounds.

Reasonable variations are not to be regarded as a departure from thescope of the invention. It will be obvious that the thus describedinvention may be varied in many ways by those skilled in the art.

The invention claimed is:
 1. A compound of Formula (I)

or a stereoisomeric form thereof, wherein: R is selected from the groupconsisting of C₁₋₄alkyl optionally substituted with 1-3 halosubstituents; R¹ is hydrogen; R² is C₁₋₄alkyl; R³ is in each instance anindependently selected halo substituent; n is an integer selected from 1and 2; R⁴ is selected from (a) and (b):

wherein R⁵ and R⁶ are each independently selected from the groupconsisting of aryl and heteroaryl, each of which may be optionallysubstituted with one or more substituents each independently selectedfrom the group consisting of halo, —CN, C₁₋₄alkyl optionally substitutedwith one or more halo substituents, and C₁₋₄alkyloxy optionallysubstituted with one or more halo substituents; wherein aryl is phenyl;wherein heteroaryl is a 5-membered aromatic heterocycle selected fromthe group consisting of oxazole and pyrazole; or is a 6-memberedaromatic heterocycle selected from the group consisting of pyridinyl,pyrimidinyl and pyrazinyl; or a pharmaceutically acceptable additionsalt or a solvate thereof.
 2. The compound of claim 1, wherein R⁴ is

wherein R⁵ is heteroaryl, optionally substituted with one or moresubstituents each independently selected from the group consisting ofhalo, —CN, C₁₋₄alkyl optionally substituted with one or more halosubstituents, and C₁₋₄alkyloxy; wherein heteroaryl is a 5-memberedaromatic heterocycle selected from oxazole and pyrazole; or is a6-membered aromatic heterocycle selected from the group consisting ofpyridinyl, pyrimidinyl and pyrazinyl.
 3. The compound of claim 1, havingthe configuration shown in Formula (I′)

wherein Ar is


4. A pharmaceutical composition comprising a therapeutically effectiveamount of a compound of claim 1 and a pharmaceutically acceptablecarrier.
 5. A process for preparing a pharmaceutical composition asdefined in claim 4, characterized in that a pharmaceutically acceptablecarrier is intimately mixed with a therapeutically effective amount of acompound of claim
 1. 6. A method of treating or preventing Alzheimer'sDisease, comprising administering to a subject in need thereof, atherapeutically effective amount of a compound of claim
 1. 7. A methodof treating or preventing a disease or condition selected fromneurocognitive disorder due to Alzheimer's disease, dementia of theAlzheimer's type, and senile dementia of Alzheimer's type comprisingadministering to a subject in need thereof, a therapeutically effectiveamount of a compound of claim
 1. 8. A method of treating or preventingAlzheimer's Disease, comprising administering to a subject in needthereof, a therapeutically effective amount of a pharmaceuticalcomposition as defined in claim
 4. 9. A method of treating or preventinga disease or condition selected from neurocognitive disorder due toAlzheimer's disease, dementia of the Alzheimer's type, and seniledementia of the Alzheimer's type, comprising administering to a subjectin need thereof, a therapeutically effective amount of a pharmaceuticalcomposition according to claim
 4. 10. The method of claim 9, wherein thedisease or condition is neurocognitive disorder due to Alzheimer'sdisease.